PHYS222 Exam 1

A 5 m long straight wire carries a current of 5 A directed north (ignore the rest of the circuit). The magnitude of the force on this section of wire in a region where a uniform 5 T magnetic field points south is

0

Let E = 4 N/C in the x direction and B = 4 T in the -z direction. An electron is moving in the y-direction with speed 1m/s. What is the magnitude of the acceleration of the electron in m/s2?

0

In the circuit shown, two capacitors and a resistor in series are connected to a battery. Initially the switch is open. What is the current through the resistor a long time after the switch has been closed?

0A (because it's been closed for a really long time)

Analyze the circuit shown below to find the total power supplied by the battery in mW.

10.3 Resistance in series = 1.5 + 2.5 = 4Ω (bottom) Resistance in parallel = 1/4 + 1/4 = 2/4 = 1/2Ω (bottom and middle) Resistors in series = 1.5 + 2 = 3.5kΩ >>> 3500Ω (top and combo) V = IR I = V/R = 6V/3500Ω P = IV = (6/3500)(6) = 0.010286W = 10.3 mW

Consider a very long solenoid with radius R and length L (R << L). The magnetic field at the center of the solenoid is B0. A second solenoid is constructed that has twice the radius, twice the length, and carries twice the current as the original solenoid, but has the same number of turns per meter. The magnetic field at the center of the second solenoid is...

2B0

The figure below shows the electric field lines for a system of two point charges. Point charge q2 has a charge of 2 microCoulomb. What is the charge of point charge q1?

8 microCoulomb

Assume that the potential V is higher at point A than at point B. Which statement then is correct?

A positive charge gains electrostatic potential energy when it moves from point B to point A.

The three-point charges shown in the figure form an equilateral triangle with sides 4.9 cm long. What is the electric potential (relative to infinity) at the point indicated with the dot, which is equidistant from all three charges? Assume that the numbers in the figure are all accurate to two significant figures. (k = 1/4πε0 = 9.0 × 10^9 N · m^2/C^2) (triangle with 2nC positive charge on top and two -1nC negative charges at the bottom of the triangle) A) 1300 V B) 0.00 V C) 1900 V D) 640 V

B) 0.00 V

A bulb (i.e., a resistor) is connected in series to a switch, a battery, and an uncharged capacitor. At t = 0, the switch is closed. Which of the following best describes the brightness of the bulb as a function of time?

C

Three pairs of conducting plates (capacitors) are shown in the figure below. Pair B has the same separation as pair A but twice the plate area. Pair C has the same area as pair A but half the separation between the plates. The insulating material between the plates of all capacitors is the same. Rank the pairs of plates according to their capacitance.

C = B > A

A memory cell in a computer contains a capacitor to store charge. Charge being stored or not being stored corresponds to the binary digits 1 and 0. To pack the cells more densely, trench capacitors are often used in which the plates of a capacitor are mounted vertically along the walls of a trench etched into a silicon chip. If we have a capacitance of 50*10-15 F and each plate has an area of 30*10-12 m2 (micron-sized trenches), what is the plate separation?

C = ε0 A/d d= A ε0/C = (30x10^-12) ((8.854x10^-12)/(50x10^-9)) = *5x10^-9 m*

If the power rating of a 400-Ω resistor is 0.800 W, what is the maximum voltage that can safely be connected across the resistor? A) 110 V B) 1.80 V C) 17.9 V D) 170 V

C) 17.9 V

An ideal voltmeter has A. zero resistance. It should be connected in parallel with the circuit element being measured. B. zero resistance. It should be connected in series with the circuit element being measured. C. infinite resistance. It should be connected in parallel with the circuit element being measured. D. infinite resistance. It should be connected in series with the circuit element being measured. E. none of the above.

C. infinite resistance. It should be connected in parallel with the circuit element being measured.

The SI unit of capacitance is Farad (F). This is the same as...

C/V

The electric field lines around an electric dipole are best represented by which, if any, of the diagrams in figure? (image link: https://www.chegg.com/homework-help/questions-and-answers/1-electric-field-lines-around-electrical-dipole-best-represented-following-diagrams-q2941878 )

D

A 5 m long straight wire carries a current of 5 A directed north (ignore the rest of the circuit). The magnitude of the force on this section of wire in a region where a uniform 5 T magnetic field points south is A) 1 N B) 125 N C) 25 N D) 0

D) 0

An electron is initially moving to the right when it enters a uniform electric field directed upwards.Which trajectory shown below will the electron follow? A) trajectory W B) trajectory X C) trajectory Y D) trajectory Z

D) trajectory Z

A large, metallic, spherical shell has no net charge. It is supported on an insulating stand and has a small hole at the top. A small tack with charge Q is lowered on a silk thread through the hole into the interior of the shell. What is the charge on the inner surface of the shell? A) Q B) Q/2 C) 0 D) - Q

D)- Q

A 9 V battery is rated at 80 Ah. It can deliver a current of 80 A for one hour, or a current of 40 A for 2 hours, etc. What is the total energy stored in the battery?

E = Pt = VIt = (9V)(80Ah)(60min/hr)(60sec/min) = 2600000J = *2.6 mJ*

Find the magnitude of the electric field produced by a point charge q = 5.74 nanoCoulomb a distance r = 3.9 meters from the charge in units of N/C. k = 9*10^9 (Nm^2)/C^2

E = kq/r^2 = [(9*10^9 (Nm^2)/C^2)(5.75 x10^-9 C)] / (3.9m^2) = *3.4 N/C*

A parallel combination of resistors has an equivalent (or effective) resistance of 2 Ω. Which one of the following is true?

Each of the individual resistances is greater than 2 Ω.

A wire carries a steady current of 2.8 A. A straight section of the wire is 0.64 m long and lies along the y-axis within a uniform field B = 1.48 T in the z-direction. What is magnitude of the magnetic force on the section of wire in N.

F = IL x B = (2.8A)(0.64m) x (1.48T) = *2.65*

An electron (|q| = 1.6*10-19 C, m = 9.1*10-31 kg) is suspended at rest in a uniform electric field of magnitude E. Its weight mg (g = 9.8 m/s2) near the Earth's surface is exactly canceled by the electrostatic force. Determine the magnitude of the electric field E in units of pN/C. (1 pN = 10-12 N)

F = qE E = F/q = mg / q = (9.1x10^-31)(9.8) / (1.6x10^-19) = 5.57x10^-11 N/C = *55.7 pN/C*

A positive charge is placed at one of 3 locations in a region where the electric field is uniform. Compare the magnitude F of the electric force on the charge at the different locations.

F is the same at all locations, but not zero.

Three resistors connected in series carry currents labeled I1, I2, I3, respectively. Which of the following expresses the value of the total current IT in the system made up of the three resistors?

IT = I1 = I2 = I3

Which of the following statements are true? (a) The electric field of a point charge always points away from the charge. (b) All macroscopic charges Q can be written as Q = ±Ne, where N is an integer and e is the charge of the electron. (c) Electric field lines never diverge from a point in space. (d) Electric field lines never cross at a point in space.

Only statements (b) and (d) are true.

Which of the following statements are true? (a) The electric field of a point charge always points away from the charge. (b) All macroscopic charges Q can be written as Q = ±Ne, where N is an integer and e is the charge of the electron. (c) Electric field lines never diverge from a point in space. (d) Electric field lines never cross at a point in space.

Only statements b and d are true

Two 4.9 microCoulomb charges are 4.1 m apart. How much energy (in milliJoule) went into assembling these two charges?

PE = kq1q2 / r = [(9x109 Nm2/C2)(4.9x10-6C)(4.9x10-6C)] / 4.1m = 0.05270 J = *52.70 mJ*

Two 1.5 microCoulomb charges are 2.4 m apart. How much energy (in milliJoule) went into assembling these two charges?

PE = kq1q2 / r = [(9x109)(1.5x10-6C)(1.5x10-6C)] / 2.4m = 0.00844 J = *8.4 mJ*

The paths of several particle moving through a region with a magnetic field pointing into the page are shown. Which particles are positively charged?

Particles 1 and 5

Two light bulbs, one rated at 50 W and a second rated at 100 W, are both supposed to be connected to a 110 V source of emf. Which one of the following is true?

The 50 W bulb has twice the resistance as the 100 W bulb.

5 microCoulomb of excess negative charge is placed on a previously neutral conductor. What happens to this charge if the conductor is left undisturbed?

The excess charge distributes itself over the surface of the conductor so that the interior is free of electric fields.

Two parallel wires are carrying currents in opposite directions as shown. Wire #1 has a current I1 that is out of the page, whereas wire #2 has a current I2 that is into the page. What effect does the magnetic field from wire #1 have on wire #2? (image link: https://www.studyblue.com/notes/note/n/physics-exam-1/deck/15379901 )

The field exerts a force on wire #2 (directed right).

Assume the voltage across the ends of a wire is doubled. If the material obeys Ohm's law, which one of the following statements concerning the resistance of the wire is true?

The resistance is not changed.

The magnetic domains in a non-magnetized piece of iron are characterized by which orientation?

They are oriented randomly

If 500 J of work are required to carry a 40 C charge form one point to another, the potential difference between these two points is

V = W/Q >>> potential difference = work/charge = 500J/40.0C = *12.5*

Which is correct language usage?

Voltage across a resistor, current through a resistor.

Which one of the following best illustrates magnetic field lines associated with the bar magnets shown?

a

A charged insulator and an uncharged metal...

always attract one another

An ideal voltmeter

has infinite resistance and should be connected in parallel with a circuit element being measured.

An ideal ammeter

has zero resistance and should be connected in series with a circuit element being measured.

A positive charge is moving with velocity v in a region with magnetic field B. What is the direction of the force on the particle?

into the page

A capacitor of 100 microFarads and a resistor of 1000 Ohms are in series. The time constant of this circuit

is 0.1s

Compared to the effective resistance of two resistors connected in series, the effective resistance of the same two resistors connected in parallel is...

lower

Compared to the effective resistance of two resistors connected in series, the effective resistance of the same two resistors connected in parallel is

lower.

A wire carries a current I as shown below. The magnetic field at the position P points

out of the page

Two negative point charges with the same charge -q and a point P are located as shown, at the vertices of an equilateral triangle. What is the direction of the electric field due to the two point charges at point P? (image point is to the left and both are negative charges)

the +x direction

If the current through a long solenoid is doubled, while the coils length is also doubled, keeping the total number of turns constant, the magnetic field at a point inside near the center is

unchanged

If the charge on each of two identical tiny spheres is doubled while their separation is reduced by a factor of 2, their force of interaction...

will increase by a factor of 16. (Use F=kq1q2/r^2)

A cubical closed surface has N inward electric flux lines passing through one face and N outward electric flux lines passing through the opposite face as shown in the figure.

0 because total flux through the closed surface = constant (# of field lines leaving - # of field lines entering) = charge inside/ε0

The voltage at the terminals of an automobile battery is 12.0 V when no current is drawn. When the starter motor is running, it draws a current of 100 A and the battery voltage falls to 10.0 V. What is the internal resistance of the battery?

0.02 Ω

Two resistors are in parallel. When the current at point 1 is 0.15 A, and the current at point 2 is 0.05 A, what is the current at point 3? point 1 is next to the battery source, point 2 is by the first resistor closest to the battery, and point 3 is by the second resistor in parallel to the first. (like the figure, but without the third far-right resistor)

0.1A

In the circuit shown, two capacitors and a resistor in series are connected to a battery. Initially the switch is open. What is the current through the resistor a long time after the switch has been closed?

0A

Three pithballs are suspended from thin threads. Various objects are then rubbed against other objects (nylon against silk, glass against polyester, etc.) and each of the pithballs is charged by touching them with one of these objects. In one set of experiments, it is found that pithballs 1 and 2 repel each other and that pithballs 2 and 3 attract each other. From this we can conclude that...

1 and 3 carry charges of opposite sign

What is the current through the battery in the circuit? (square series circuit with an 8V battery, and 2 4Ω resistors)

1A

A current loop lies in the xy-plane. It has a magnetic dipole moment of 0.1 A-m2 along the z-axis. A uniform 2 T magnetic field parallel to the xz-plane makes a 30° angle with the x-axis. What is the magnitude of the net torque on the current loop?

30º x 2 for xy-plane angle? T = µBsinθ = (0.1)(2)sin(60) = *0.17Nm*

Three point charges lie at the vertices of an equilateral triangle as shown. All three charges have the same magnitude, but charge #1 is positive (+q) and charges #2 and #3 are negative (-q). The net electric force that charges #2 and #3 exert on charge #1 is in A. the +x-direction. B. the -x-direction. C. the +y-direction. D. the -y-direction. E. none of the above. (image link: https://www.chegg.com/homework-help/questions-and-answers/2-three-point-charges-lie-vertices-equilateral-triangle-shown-three-charges-magnitude-char-q9929857 )

A. the +x-direction.

Two long, straight wires are oriented perpendicular to the xy-plane. They carry currents of equal magnitude I in opposite directions as shown. At point P, the magnetic field due to these currents is in A. the positive x-direction. B. the negative x-direction. C. the positive y-direction. D. the negative y-direction. E. none of the above. (image link: https://www.chegg.com/homework-help/questions-and-answers/two-long-straight-wires-oriented-perpendicular-xy-plane-carry-currents-equal-magnitude-opp-q16732433 )

A. the positive x-direction.

Equipotential lines around two point charges are shown. What is the direction of the electric field at points A and B?

A: to the right B: up

Which of the following statements about a conductor in electrostatic equilibrium is false? (a) The electric field inside the conductor is zero. (b) Just outside the conductor, the electrostatic field is perpendicular to its surface. (c) The net charge inside the conductor is zero, all excess charge resides on the surface. (d) A charge located within a hole in a conductor at equilibrium feels no force from charges outside the conductor.

All of the above statements are true.

Find the current I (in A) in a long straight wire that would produce a magnetic field of 4.2*10-4 T at a distance of 3.82 cm from the wire.

B = µ0 I / 2πr (4.2*10^-4 T) = (4π*10^-7)( I ) / (2*π*0.0382m) I = (4.2*10^-4 T)(2*π*0.0382m) / (4π*10^-7) = *80.2*

A long straight vertical wire carries a 8 A current upwards along the z axis. Find the magnetic field produced by this wire (magnitude and direction) on the x-axis at x = 4 m.

B = µ0 I / 2πr = (4π*10^-7)(8A) / 2π(4m) = 0.0000004T = 0.4µT 0.4µT in the positive y-direction

Positive and negative charges of the same magnitude, as well as a small positive test charge are placed as shown in each of the four figures. Rank the magnitude of the force the test charge feels in each of the four figures.

B > A > C > (D=0)

Two small objects each with a net charge of Q exert a force of magnitude F on each other. If the distance between these charges is reduced to one third, what will be the magnitude of the force? A. 27F B. 9F C. F D. F/9 E. None of the above

B. 9F

An ideal ammeter has A. zero resistance. It should be connected in parallel with the circuit element being measured. B. zero resistance. It should be connected in series with the circuit element being measured. C. infinite resistance. It should be connected in parallel with the circuit element being measured. D. infinite resistance. It should be connected in series with the circuit element being measured. E. none of the above.

B. zero resistance. It should be connected in series with the circuit element being measured.

When a negative charge moves opposite to the direction of the electric field, A.the field does positive work on it and the potential energy increases. B.the field does positive work on it and the potential energy decreases. C.the field does negative work on it and the potential energy increases. D.the field does negative work on it and the potential energy decreases. E.the field does zero work on it and the potential energy remains constant.

B.the field does positive work on it and the potential energy decreases.

Three particles travel through a region of space where the magnetic field is out of the page, as shown in the figure. What are the signs of the charges of these three particles? A) 1 is neutral, 2 is negative, and 3 is positive. B) 1 is neutral, 2 is positive, and 3 is negative. C) 1 is negative, 2 is neutral, and 3 is positive. D) 1 is positive, 2 is negative, and 3 is neutral. E) 1 is positive, 2 is neutral, and 3 is negative.

C) 1 is negative, 2 is neutral, and 3 is positive.

The magnetic force on a current-carrying wire in a magnetic field is the strongest when A) the current is in the direction of the magnetic field lines. B) the current is at a 180°angle with respect to the magnetic field lines. C) the current is perpendicular to the magnetic field lines. D) the current is in the direction opposite to the magnetic field lines. E) the current is at a 0°angle with respect to the magnetic field lines.

C) the current is perpendicular to the magnetic field lines.

When two or more capacitors are connected in parallel across a potential difference A) each capacitor carries the same amount of charge. B) the equivalent capacitance of the combination is less than the capacitance of any of the capacitors. C) the potential difference across each capacitor is the same. D) All of the above choices are correct. E) None of the above choices are correct.

C) the potential difference across each capacitor is the same.

An electron has an initial velocity to the south but is observed to curve upward as the result of a magnetic field. This magnetic field must have a component A)to the north B)downward C)to the west D)upward E)to the east.

C) to the west

Two parallel long wires each have a large current I flowing out of the page, as shown. In what direction does the magnetic field point at position P? ---I-------------P---I---- A)up B)right C)down D)left

C)down

In the circuit shown in (a), the two bulbs A and B are identical. Bulb B is removed and the circuit is completed as shown in (b). Compared to the brightness of bulb A in (a), bulb A in (b) is A. just as bright. B. less bright. C. brighter. D. any of the above, depending on the rated wattage of the bulbs. (image link: https://www.chegg.com/homework-help/questions-and-answers/circuit-shown-two-bulbs-b-identical-bulb-b-removed-circuit-completed-shown-b--compared-bri-q15635601 )

C. brighter.

In the circuit shown, the two bulbs A and B are identical. Compared to bulb A, A. bulb B glows more brightly. B. bulb B glows less brightly. C. bulb B glows equally brightly. D. the answer depends on whether the mobile charges in the wires are positively or negatively charged. E. the answer depends on whether the same kind of wire is used in all parts of the circuit.

C. bulb B glows equally brightly.

Two capacitors have an equivalent capacitance of 8 pF if connected in parallel, and 2 pF, if connected in series. Find C1 and C2.

C1 = 4 pF, C2 = 4 pF

We observe that a moving charged particle experiences no magnetic force.From this we can definitely conclude that A) the particle must be moving parallel to the magnetic field. B) the particle is moving at right angles to the magnetic field. C) no magnetic field exists in that region of space. D) either no magnetic field exists or the particle is moving parallel to the field. E) either no magnetic field exists or the particle is moving perpendicular to the field.

D) either no magnetic field exists or the particle is moving parallel to the field.

Three point charges lie at the vertices of an equilateral triangle as shown. All three charges have the same magnitude, but charges #1 and #2 are positive (+q) and charge #3 is negative (-q). The net electric force that charges #2 and #3 exert on charge #1 is in A. the +x-direction. B. the -x-direction. C. the +y-direction. D. the -y-direction. E. none of the above. (image link: https://www.chegg.com/homework-help/questions-and-answers/a213-three-point-charges-lie-vertices-equilateral-triangle-shown-three-charges-charge-magn-q8105577 )

D. the -y-direction.

A cube with sides of area 78 cm^2 contains a 22.1 nanoCoulomb charge. Find the flux of the electric field through the surface of the cube in units of Nm^2/C.

I = q/ε = 22.1x10^-9 C / 8.85x10^-12 Nm^2/C) = *2497.2 Nm^2/C*

Two very flat, metallic plates separated a distance d have a potential difference of 600 Volts between them as shown below. A proton and positron (which is a positively charged electron) are released from rest at the surface of the metal plate held at 600 Volts. Which of the following statement(s) is (are) correct? I. The positron's acceleration is larger than the proton's acceleration. II. The positron's acceleration is the same as the proton's acceleration. III. The positron's acceleration is smaller than the proton's acceleration. IV. The positron's kinetic energy will be larger than the proton's kinetic energy right before the particles hit the 0 Volt plate. V. The positron's kinetic energy will be the same as the proton's kinetic energy right before the particles hit the 0 Volt plate. VI. The positron's kinetic energy will be smaller than the proton's kinetic energy right before the particles hit the 0 Volt plate.

I and V only

Charges Q1 and Q2 are situated as shown below. The electric field is zero at point P. What conclusions can be drawn about the charges Q1 and Q2? I. The magnitudes of Q1 and Q2 are equal. II. The magnitude of Q1 is greater than the magnitude of Q2. III. The magnitude of Q1 is less than the magnitude of Q2. IV. Q1 and Q2 have the same sign. V. Q1 and Q2 have different signs. (image link: https://www.chegg.com/homework-help/questions-and-answers/charges-q1-q2-situated-shown--electric-field-zero-point-p-conclusions-drawn-charges-q1-q2--q30781340 )

II and IV are correct. The magnitude of Q1 is greater than the magnitude of Q2 and Q1 and Q2 have the same sign.

An electron moves perpendicular to a magnetic field. The magnetic force on the electron points in the direction shown in the figure. What is the direction of B? (image link: https://www.chegg.com/homework-help/questions-and-answers/part-long-wire-carries-20-left-right-electron-10x10-2-m-wire-traveling-right-speed-10x108--q10924115 )

Into the page F = qv x B (-i) = (-q)(-j) x B -i = j x B B = -k

Which of the statements below are true? (1) Whenever electrons are in motion, a current flows. (2) A "D" battery is labeled as providing 1.5 volts. This voltage characterizes the amount of current that the battery supplies when it is installed in an electronic device. (3) You plug a space heater into an outlet and the temperature of the heating coils increases for some time before it becomes stable. As the temperature of the coils increases, their resistance increases, and therefore the power consumed by the space heater increases.

None of these statements are true.

A uniform magnetic field is directed into the page. A charged particle, moving in the plane of the page, follows a clockwise spiral of decreasing radius. A reasonable explanation is that...

The charge is negative and slowing down

Using the image below as your only evidence, what MUST be true about charged objects 1 and 2?

The charge on both objects has the same sign.

You double the voltage across a certain conductor and you observe the current increases three times. Does the conductor obey Ohm's law?

The conductor does not obey Ohm's Law.

A mass spectrometer is to be used to separate protons from deuterium nuclei. A deuterium nucleus has the same charge and twice the mass as a proton, since it contains an extra neutron. Both the deuterium and the proton nuclei are accelerated by the same voltage. Which of the following statements is true?

The deuterium will have a larger radius of curvature, since it is more massive.

Consider the situation shown below. A wire carrying a current flowing into the page is placed between the poles of a horseshoe magnet. Which statement is correct regarding the magnetic force on the wire?

The magnetic force of the wire points to the left.

The electric field-line diagram visualizes the electric field produced by a pair of charges. A negative test charge is placed at point P directly between the two charges in the diagram. (image link: https://www.studyblue.com/notes/note/n/physics-exam-1/deck/15379901 )

The test charge will accelerate towards the right.

A solenoid is connected to a battery as shown. A bar magnet is placed nearby. What is the direction of the magnetic force the solenoid exerts on the bar magnet?

To the left (The north pole of the coil is on the right side, the south pole is on the left side, facing the south pole of the magnet.)

What is the direction of the Coulomb force on the charge pointed at by the arrow? (Charge is given in arbitrary units.)

Towards the right

What is the current through the battery in the circuit shown below? (Square series circuit with 8V battery, 4Ω resistor directly across, and 4Ω resistor in between them on the left side, the right side is empty) A) 1 A B) 4 A C) 2 A D) 8 A

V = IR 8V = I (4+4 = 8Ω) A) 1 A

Two 1.9 microCoulomb charges are 3 m apart. What is the potential at each charge due to the other in V?

V = kq / r = [(9x109 Nm2/C2)(1.9x10-6C)] / 3m = *5700V*

A real, not ideal, battery is connected as shown. Rank the potential difference across the terminals from the greatest to the smallest.

V4 > V3 > V2 > V1

In the figure, the cube is 40 cm on each edge. Four straight-line segments, ab, bc, cd, and da form a closed loop that carries a current I = 5 A. A uniform magnetic field B = 0.02 T is in the positive y-direction. What is the magnitude of the magnetic force on the wire segment da?

Zero (The force on a straight wire of length L in a uniform field B is F = IL × B.The magnitude of the force is F = ILBsinθ, where θ is the smallest angle between the directions of B and the current flow. The angle between B and the current flow in the segment da is 90o, sinθ = 1. L is the length of the diagonal.)

Two point charges Q1 and Q2 of equal magnitudes and opposite signs are positioned as shown in the figure. Which of the arrows best represents the net electric field at point P due to these two charges? a. A b. B c. C d. D e. the field is equal to zero at point P (image link: https://www.chegg.com/homework-help/questions-and-answers/two-charges-q1-q2-equal-magnitudes-opposite-signs-positioned-shown-fig-21-7-shown-arrows-r-q2667835 )

a. A

A proton is initially at rest at x = d and an electron is initially at rest at x = -d. At the same instant they are released. They subsequently

collide close to x = d (because the proton has the larger mass and smaller acceleration)

You wish to double the power dissipated by a heating device. You could...

double the resistance while keeping the current the same.

A proton is released near the equator and falls toward the earth under the influence of gravity. The magnetic force on the proton will be toward the

east

Consider a uniform electric field, for example the field inside a parallel plate capacitor, as shown. If a proton is taken from location B to location C, how does its potential energy change? +++++++++++++++++++++++++++++ I A I I B I I I I I I I I I I I C I v v v v v -----------------------------

it decreases

The figure below shows a proton (q = +e) at one instant with velocity V pointing along the positive x-axis. The proton is moving through a magnetic field B that points along the positive y-axis. At the instant shown the magnetic force on the proton...

points in the positive z-direction

You have just pulled your clothes from the dryer and find that a sock is clinging to your jeans with static electricity. You pull the two apart. As the jeans and the sock move apart, the force between them becomes weaker because...

the force between the electric charges becomes weaker with increasing distance.

A stationary positive charge +Q is located in a magnetic field B, which is directed toward the right as indicated. The direction of the magnetic force on Q is

the magnetic force will be zero

A particle with a positive charge moves in the xz-plane as shown. The magnetic field is in the positive z-direction. The magnetic force on the particle is in (image link Q27.2: http://www2.hawaii.edu/~plam/ph272_summer/L7/27_ClickerQuestions_Lam.pdf )

the negative y-direction.

The figure below shows the equipotential surfaces of an electric dipole in the xy-plane. The x and y scales are in units of meter. The charge on the left is positive. Each color change represents a a change in the potential of 5 V. Estimate the magnitude and direction of the electric field in units of V/m = N/C at x = 5.5 m, y = 13 m.

~11 V/m to the left

Suppose that a picture of electric field lines is drawn following the convention that 4 field lines emerge from a small sphere with 4 pC of charge. In this picture there is an irregular closed surface, the interior of which is hidden, as shown below. The net amount of charge inside the closed surface must be...

+4 pC

Each of three objects has a net charge. Objects A and B attract one another. Objects B and C also attract one another, but objects A and C repel one another. Which one of the following table entries is a possible combination of the signs of the charges on these three objects? A B C

- + -

In the early universe and in stars, deuterium nuclei are produced from the combination of one proton and one neutron, with the release of a gamma ray. What is the charge on a deuterium nucleus in units of qe = 1.6*10^-19 C?

1

Which of the points shown in the figure below are at the same potential?

1 and 4

What is the equivalent resistance in the circuit shown in the figure? A) 50 Ω B) 80 Ω C) 55 Ω D) 35 Ω (image link: https://www.chegg.com/homework-help/questions-and-answers/equivalent-resistance-circuit-shown-figure-55-80-35-50-two-40-resistors-connected-parallel-q6726167 )

A) 50 Ω

The resistivity of aluminum is 58% higher than that of copper. A copper high voltage line has diameter 1 cm. If is replaced by an aluminum line of the same resistance and length, the aluminum line has diameter

1.26 cm

A capacitor with a charge of 6.8 C has its terminals shorted by a metal wire so that the charge flows off within 3.7 s. What is the average current flowing during that time in Ampere (A)?

1.84

A current of 4.00 A flows through the heating element of heater converting 500 J of electrical energy into thermal energy every second. What is the voltage across the ends of the heating element?

125V

Determine the equivalent resistance between points A and B in the following circuit.

15 kΩ

A wire carries a steady current of 15.8 A. What total charge (in C) passes through a cross-sectional area of the wire in a 11.6 s time interval?

183.3

The figure below shows different ways to connect a light bulb to a battery with wires. Which of the bulbs will light up?

5

A high voltage transmission line has an aluminum cable of diameter 3.3 cm and is 171 km long. The resistivity of Aluminum is 2.8*10-8 Ωm. What is the resistance of this cable in Ω?

5.6

A high voltage transmission line has an aluminum cable of diameter 3.0 cm and is 200 km long. The resistivity of Aluminum is 2.8*10-8 Ωm. What is the resistance of this cable?

7.9 Ω

Where an electric field line crosses an equipotential surface, the angle between the field line and the equipotential is

90°

A negative charge is moved from point A to point B along an equipotential surface. Which of the following statements must be true for this case? A) No work is required to move the negative charge from point A to point B. B) The work done on the charge depends on the distance between A and B. C) The negative charge performs work in moving from point A to point B. D) Work is required to move the negative charge from point A to point B. E) Work is done in moving the negative charge from point A to point B.

A) No work is required to move the negative charge from point A to point B.

The figure shows three electric charges labeled Q1, Q2, Q3, and some electric field lines in the region surrounding the charges. What are the signs of the three charges? A)Q1 is positive, Q2 is negative, Q3 is positive. B)Q1 is positive, Q2 is positive, Q3 is negative. C)Q1 is negative, Q2 is positive, Q3 is negative. D)All three charges are negative.E)All three charges are positive.

A) Q1 is positive, Q2 is negative, Q3 is positive.

A conducting sphere contains positive charge distributed uniformly over its surface. Which statements about the potential due to this sphere are true? All potentials are measured relative to infinity. (There may be more than one correct choice.) A) The potential at the center of the sphere is the same as the potential at the surface. B) The potential at the center of the sphere is zero. C) The potential is lowest, but not zero, at the center of the sphere. D) The potential at the surface is higher than the potential at the center. E) The potential at the center is the same as the potential at infinity.

A) The potential at the center of the sphere is the same as the potential at the surface.

An electron moving along the +x-axis enters a magnetic field. If the electron experiences a magnetic deflection in the -y direction, then the magnetic field must have a component A) along the -z-axis B) along the -x-axis C) along the -y-axis D) along the +y-axis E) along the +z-axis

A) along the -z-axis

Suppose a region of space has a uniform electric field, directed towards the right, as shown in the figure. Which statement about the electric potential is true? A)The potential at points A and B are equal, and the potential at point C is lower than the potential at point A. B)The potential at point A is the highest, the potential at point B is the second highest, and the potential at point C is the lowest. C)The potential at points A and B are equal, and the potential at point C is higher than the potential at point A. D)The potential at all three locations (A, B, C) is the same because the field is uniform. (image link: https://www.chegg.com/homework-help/questions-and-answers/10-suppose-region-space-uniform-electric-field-directed-towards-right-shown-figure-stateme-q24172936 )

A)The potential at points A and B are equal, and the potential at point C is lower than the potential at point A.

A negatively charged rod is brought near a neutral metal sphere. Which of the following is true? A. There is an attractive force between the rod and sphere. B. There is a repulsive force between the rod and sphere. C. There is no electric force between the rod and sphere.

A. There is an attractive force between the rod and sphere.

Earth and Moon attract each other via the gravitational force. Which force diagram correctly represents the magnitude and direction of the force on each of these objects? A.A B.B C.C D.D E.None of them

B

Determine the current in the 7.0-Ω resistor for the circuit shown in the figure. Assume that the batteries are ideal and that all numbers are accurate to two significant figures. A) 0.28 A B) 1.6 A C) 2.1 A D) 1.3 A

B) 1.6 A

At a distance D from a very long (essentially infinite) uniform line of charge, the electric field strength is 4000 N/C. At what distance from the line will the field strength to be 1000 N/C? A) D/2 B) 2D C) D/√2 D) D/4 E) √2D

B) 2D

Two electrons are 20.0 mm apart at closest approach. What is the magnitude of the maximum electric force that they exert on each other? (e = 1.60 × 10-19 C, k = 1/4πε0 = 9.0 109 N · m2/C2) A) 5.8 × 10^-27 N B) 5.8 × 10^-25 N C) 2.3 N D) 2.3 × 10^10 N

B) 5.8 × 10^-25 N

The electric potential energy of two point charges approaches zero as the two point charges move farther away from each other. If the three point charges shown here lie at the vertices of an equilateral triangle, the electric potential energy of the system of three charges is A)positive B)Negative C)zero D)either negative or positive (image link: https://www.chegg.com/homework-help/questions-and-answers/electric-potential-energy-two-point-charges-approaches-zero-two-point-charges-move-farther-q37640819 )

B) Negative

For the graph shown in the figure, what physical quantity does the slope of the graph represent for ohmic material? A) power B) resistance C) 1/(resistivity) D) resistivity E) 1/(resistance) (image link: https://www.chegg.com/homework-help/questions-and-answers/graph-shown-figure-physical-quantity-slope-graph-represent-ohmic-material-power-b-resistiv-q13413669 )

B) resistance

A system of four capacitors is connected across a 90-V voltage source as shown in the figure. What is the equivalent capacitance of this system? A)15 μF B)3.3 μF C)3.6 μF D)1.5 μF (image link: https://www.chegg.com/homework-help/questions-and-answers/system-four-capacitors-connected-across-90-v-voltage-source-shown-figure-charge-40-uf-capa-q7031229 )

B)3.3 μF

Which one of the following statements is correct? A) When a current-carrying wire is in your left hand, with your thumb in the direction of the current, your fingers point in the direction of the magnetic field lines. B)When a current-carrying wire is in your right hand, with your thumb in the direction of the current, your fingers point in the direction of the magnetic field lines. C)When a current-carrying wire is in your right hand, with your thumb in the direction of the current, your fingers point opposite to the direction of the magnetic field lines.

B)When a current-carrying wire is in your right hand, with your thumb in the direction of the current, your fingers point in the direction of the magnetic field lines.

A particle with a positive charge moves in the xz-plane as shown. The magnetic field is in the positive z-direction. The magnetic force on the particle is in A)the negative x-direction B)the negative y-direction C)the positive y-direction D)the positive x-direction (image link: https://www.chegg.com/homework-help/questions-and-answers/particle-positive-charge-moves-xz-plane-shown-magnetic-field-positive-z-direction-magnetic-q24917608 )

B)the negative y-direction

Two small objects each with a net charge of Q exert a force of magnitude F on each other. We replace one of these with a charge 4Q. What is the magnitude of the force after the replacement? A. 16F B. 4F C. F D. F/4 E. None of the above

B. 4F

The electric potential energy of two point charges approaches zero as the two point charges move farther away from each other. If the three point charges shown here lie at the vertices of an equilateral triangle, the electric potential energy of the system of three charges is A. positive. B. negative. C. zero. D. either positive or negative. E. either positive, negative, or zero. (image link: https://www.chegg.com/homework-help/questions-and-answers/a213-three-point-charges-lie-vertices-equilateral-triangle-shown-three-charges-charge-magn-q8105577 )

B. negative.

The figure shows, in cross section, three conductors that carry currents perpendicular to the plane of the figure. If the currents I1, I2, and I3 all have the same magnitude, for which path(s) is/are the line integral of the magnetic field equal to zero? A. path a only B. paths a and c C. paths b and d D. paths a, b, c, and d E. depends on whether the integral goes clockwise or counterclockwise around the path (image link: https://www.chegg.com/homework-help/questions-and-answers/figure-shows-cross-section-three-conductors-carry-currents-perpendicular-plane-figure-i1-p-q16383529 )

B. paths a and c

What current flows from the battery in the circuit shown in the figure? The battery is ideal, and all the numbers are accurate to two significant figures. A) 3.0 A B) 0.35 A C) 2.0 A D) 2.5 A (image link: https://www.chegg.com/homework-help/questions-and-answers/current-flows-battery-circuit-shown-figure-battery-ideal-numbers-accurate-two-significant--q7030827 )

C) 2.0 A

Two equal and opposite charges are a small distance apart, forming an electric dipole. A positive charge +q is placed above these charges, as shown in the figure, equidistant from both of them. Which diagram below best gives the direction of the net force the dipole exerts on the charge +q? *+q* *+* *-* A) upward B) left C) right D) downward

C) right

In which of the circuits below does a current exist to light the bulb? A)4 & 5 B)1 & 5 C)5 only D)4 only (image link: https://www.chegg.com/homework-help/circuits-shown-current-exist-light-bulb-chapter-23-problem-68tae-solution-9780321909107-exc )

C)5 only

Two point charges, +q and -q, are placed as shown. Rank the five points labeled A, B, C, D, and E in order of the electric potential at each point due to the two point charges, from most positive to most negative. The five points and the two point charges all lie in the same plane. A. ABCDE B. EDCBA C. CADBE D. CDEBA (image link (first question): http://www.physics.rutgers.edu/~cizewski/227_s2018/227-S18-finexam-p12.pdf )

C. CADBE

A long, straight wire lies along the y-axis and carries current in the positive y-direction. A positive point charge moves along the x-axis in the positive x-direction. The magnetic force that the wire exerts on the point charge is in A. the positive x-direction. B. the negative x-direction. C. the positive y-direction. D. the negative y-direction. E. none of the above. (image link: https://www.chegg.com/homework-help/questions-and-answers/explain-problem-moving-charges-figure-least-100-words-q7671187 )

C. the positive y-direction.

A negatively charged balloon is attracted to a neutral wooden cabinet due to polarization. Which one of the following diagrams best depict why this occurs?

D

Equipotential lines are shown. For which region is the magnitude of the electric field the greatest?

D

In the circuit, two capacitors and a resistor in series are connected to a battery. Initially the switch is open. What is the current through the resistor a long time after the switch has been closed? A) 1.25 * 10^-5 A B) 1 A C) 4 A D) 0

D) 0

If 1.5 A flows through R2, what is the emf V of the ideal battery in the figure? (Long rectangle split into two squares with the only battery at far left, a 10Ω resistor on the top to the right of the battery, and 30Ω resistor on the bottom to the right of the battery, and a 20Ω resistor on the side of the square opposite the battery. The second square of the entire rectangle has one 20Ω resistor in parallel to the first square's 20Ω resistor) A) 75 V B) 30 V C) 60 V D) 150 V

D) 150 V

Two small objects each with a net charge of Q exert a force of magnitude F on each other. We double the distance between these charges. What is the magnitude of the force? A. 16F B. 4F C. F D. F/4 E. None of the above

D. F/4

An electron (|q| = 1.6*10-19 C, m = 9.1*10-31 kg) is suspended at rest in a uniform electric field of magnitude E. Its weight mg (g = 9.8 m/s2) near the Earth's surface is exactly canceled by the electrostatic force. The electric field points...

Down

Two point charges, Q1 and Q2, are separated by a distance R. If the magnitudes of both charges are doubled and their separation is also doubled, what happens to the electrical force that each charge exerts on the other one? A) It is reduced by a factor of √(2). B) It increases by a factor of √(2) . C) It increases by a factor of 2. D) It increases by a factor of 4. E) It remains the same.

E) It remains the same.

Consider a spherical Gaussian surface of radius R centered at the origin. A charge Qis placed inside the sphere. To maximize the magnitude of the flux of the electric field through the Gaussian surface, the charge should be located A) at x= 0, y= 0, z= R/2. B) at x= 0, y= R/2, z= 0. C) at x= R/2, y= 0, z= 0. D) at the origin. E) The charge can be located anywhere, since flux does not depend on the position of the charge as long as it is inside the sphere.

E) The charge can be located anywhere, since flux does not depend on the position of the charge as long as it is inside the sphere.

Three capacitors are connected as shown in the figure. What is the equivalent capacitance between points a and b? A)7.1 μF B)12 μF C)8.0 μF D)4.0 μF E)1.7 μF (image link: https://www.chegg.com/homework-help/questions-and-answers/three-capacitors-connected-shown-thye-figure-equivalent-capacitance-points-b-17-mu-f-40-mu-q9307635 )

E)1.7 μF

The capacitors in the network shown in the figure all have a capacitance of 5.0 μF. What is the equivalent capacitance, Cab, of this capacitor network? A)5.0 μF B)20 μF C)10 μF D)1.0 μF E)3.0 μF (image link: https://www.chegg.com/homework-help/questions-and-answers/capacitors-network-shown-figure-capacitance-50-mu-f-equivalent-capacitance-cab-capacitor-n-q9307643 )

E)3.0 μF

A positive charge is moving to the right and experiences an upward magnetic force, as shown in the figure. In which direction must the magnetic field have a component? A)out of the page B)to the right C)upward D)to the left E)into the page

E)into the page

A circular loop of wire carries a constant current. If the loop is placed in a region of uniform magnetic field, the net magnetic force on the loop is A. perpendicular to the plane of the loop, in a direction given by a right-hand rule. B. perpendicular to the plane of the loop, in a direction given by a left-hand rule. C. in the same plane as the loop. D. The answer depends on the magnitude and direction of the current and on the magnitude and direction of the magnetic field. E. zero.

E. zero.

Two 10 μC charges are located at (x, y) = (0, 3m) and (3 m, 0), respectively. What is the potential due to those two charges at the location of the 1 μC charge at the origin?

PE = kq1q2/r = [(9x109)(2 x 10x10-6)]/3 = 6000 = *6.0x10^4*

Equipotential lines around several point charges are shown. What are the signs of the charges at points A and B? (image link: https://www.chegg.com/homework-help/questions-and-answers/equipotential-lines-around-several-point-charges-shown-signs-charges-points-b-cannot-deter-q39973753 )

The charge at B is positive and the charge at A is negative.

495 J of work are required to carry a 13 C charge from point 1 to point 2. What is the magnitude if the potential difference between point 1 and point 2 in units of V? Enter a number with one digit behind the decimal point. W= 495J Q = 13C

V = PE/Q = W/Q = 495J/13C = *38.1V*

Two 1 microCoulomb point charges are 2 m apart. The potential at each charge due to the other charge is

V = kq/r = (9x109)(1x10-6C)/(2m) = *4500 V*

Which of the following statements is true? a. A positive charge experiences an attractive electrostatic force toward a nearby neutral conductor. b. A positive charge experiences no electrostatic force near a neutral conductor. c. A positive charge experiences a repulsive force, away from a nearby conductor. d. Whatever the force on a positive charge near a neutral conductor, the force on a negative charge is then oppositely directed.

a. A positive charge experiences an attractive electrostatic force toward a nearby neutral conductor.