Physics 2 test 1
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.
How much energy (in milliJ) is stored in a 62 microFarad capacitor if the voltage across the capacitor is 53 V?
U = ½C(V^2) = 0.5(0.062)(53^2) = 87.08
The potential difference between the two plates of the capacitor shown below is 6.9 V. If the separation between the plates is 2 mm, what is the strength of the electric field between the plates N/C?
Units of N/C = units of V/M Change in V/change in x = 6.9/0.002 = 3450
A charged insulator and an uncharged metal
always attract one another
Which of the following statements are true about the electric field? (a) The strength of the electric field created by an object A at a point P increases by a factor of 4 is the charge on object A is doubled. (b) The strength of the electric field created by an object A at a point P decreases by a factor of 4 is the distance between A and P is doubled (c) The strength of the electric field created by an object A at a point P is unchanged if both the charge on object A and the distance between A and P are doubled.. (d) The strength of the electric field inside a conductor is zero. (e) For irregularly shaped conductors, the electric field strength is greatest around points of highest curvature. (f) The SI unit for the electric field is N/C.
b, d, e, f, only
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.
The magnetic domains in a non-magnetized piece of iron are characterized by which orientation?
they are oriented randomly
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.
Analyze the circuit shown below to find the total power supplied by the battery in mW. (link to photo) https://utk.instructure.com/assessment_questions/467298/files/718399/download?verifier=HA3N0uuDnnWvSiaZ8qKlymLWmo8pz5HwxfJUrQvq
10.3 (idk how this number was found. its on the google doc under practice problems #17)
A superconducting solenoid (coil) is used to generate a magnetic field of 10 T. If the solenoid winding has 2000 turns/m, what is the required current in the solenoid?
3979 A
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.
Equipotential lines around two point charges are shown. What is the direction of the electric field at points A ans B? (link to photo) https://utk.instructure.com/assessment_questions/467150/files/718233/download?verifier=s0JEO6PNKCjTqTSU5PosYJxdzLJnH6xmwsdN3ryv
A: to the right B: up
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. (link to photo) https://utk.instructure.com/assessment_questions/467239/files/718358/download?verifier=vLQIqjQOl3i9GQYriX0tgonCSwuAMfBjqDsfLRCo
C = B > A
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
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? (link to the photo) https://utk.instructure.com/assessment_questions/466994/files/718132/download?verifier=gHR79m5w7bbDYcQf1dioGecsKVEzQe30ko9ebNQY
D
Equipotential lines are shown. For which region is the magnitude of the electric field the greatest? (link to photo) https://utk.instructure.com/assessment_questions/467000/files/718144/download?verifier=RMPxJeQMnSQJypWvQjHLVlryMqURO7X0a0i1wVmd
D
A high voltage transmission line has an aluminum cable of diameter 3.6 cm and is 264 km long. The resistivity of Aluminum is 2.8*10-8 Ωm. What is the resistance of this cable in Ω?
Diameter of the cable is 3.6 cm so a cross sectional area is π(d/2)2= 10.18 R= [(2.8*10-8)(2.64*105)]/(10.18*10-4 ) = 7.3
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/s^2) 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^-12N)
E = mg/q ((9.1x10^31 kg)(9.8 m/s^2))/(1.6x10^-19 C) = 5.57375 X 10^51 converted to pN=55.7 pN/C
Find the magnitude of the electric field produced by a point charge q = 3.96 nanoCoulomb a distance r = 3.6 meters from the charge in units of N/C.
E=kQ/r^2 (8.99x10^9)x(3.96x10^-9)/(3.6)^2= 2.746
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 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. (link to the image) https://utk.instructure.com/assessment_questions/466995/files/718133/download?verifier=T62U871jdbP80KztZoK26HwcXZVtqy1i5ung1hzi
F is the same, but not zero
A wire carries a steady current of 0.9 A. A straight section of the wire is 1.07 m long and lies along the y-axis within a uniform field B = 1.89 T in the z-direction. What is magnitude of the magnetic force on the section of wire in N.
F=IL*B I=.9 A; L=1.07 m; B=1.89 T 0.9*1.07*1.89=1.82
Two positive point charges, each with charge q, separated by a distance d, repel each other with a force of magnitude 10 N (a). What is the magnitude of the force between two positive point charges of magnitude 6.57 q, separated by a distance 3.4 d in units of N (b)?
F=kq^2/r^2 10N=k(q2/d2) xN=k(6.57q2/3.4d2) (k is constant so it may be ignored) xN=(6.5723.42)q2/d2 xN=3.734q2/d2` The ratio in (a) of N:q2/d2 is 10:1 so multiply 3.734*10 to get the new N. 37.34N=q2/d2
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.
A current of 3.6 A flows through the heating element of heater converting 712 J of electrical energy into thermal energy every second. What is the voltage (in V) across the ends of the heating element?
P = I*V 712J = 3.6A x Voltage It would be 197.8
946 J of work are required to carry a 23 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?
Potential difference = work / charge → 946/23 = 41.1
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
Which is correct language usage?
Voltage across a resistor, current through a resistor
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? (link to photo) https://utk.instructure.com/assessment_questions/467155/files/718243/download?verifier=TwDG0g1679grS4UKL4GdgCdeGR29vtvUnmBwFXpi
c
A wire carries a current I as shown below. The magnetic field at the position P points (link to the photo) https://utk.instructure.com/assessment_questions/467021/files/718161/download?verifier=SfdGteogfEL51EfgU1X4vefMzSSJqR7tNdapByeo
out of the page
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. (link to photo) https://utk.instructure.com/assessment_questions/467297/files/718398/download?verifier=tDHmU7nk02ahAJVJhRMwvnR9mzSymVZmW9P8O9CE
~11 V/m to the left
In a series RC circuit a charged capacitor with capacitance C is being discharged though a resistor of resistance R. Plots of voltage and current versus time are shown below. Find the time constant τ of the circuit. (link to photo) https://utk.instructure.com/assessment_questions/467152/files/718242/download?verifier=bISzOyCFItGox1cJdKWIjiwAJB5LSsecoRQJHgi2
τ = 1 s
The normal of a one-turn circular loop of radius r = 3.1 cm makes an angle of 72.7 degrees with the direction of a uniform magnetic field of magnitude 2.5 T. What is the magnitude of the torque (in milliNewton m) exerted on the loop by the field when a current I = 3.9 A circulates in the loop?
τ = μBsin θ μ = 3.9A(3.14)(0.031)^2= 0.0117 A*m^2 τ = 0.0117(2.5T)(sin 72.7) = 0.02809 N*m = 28.90 mN*m
A parallel-plate capacitor initially is connected to a battery and the plates hold charge ±Q. The battery is then disconnected. If the plate spacing is now doubled, what happens?
the voltage increases
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? (link to photo) https://utk.instructure.com/assessment_questions/467303/files/718402/download?verifier=dyHCmv7AO3wD8N1mwVAL81kI0WjjI5kPPRCSj3Hl
to the left
What is the direction of the electric field produced by the -5 μC charge located at x = 5 m at the position of the -1 μC charge at the origin?
to the right
To what extent is the flow of water analogous to the flow of charge? What is NOT a correct hydrodynamic analog?
charge - volume flow rate
You wish to double the power dissipated by a heating device. You could
double the resistance while keeping the current the same.
Which diagram does not represent an electrical current?
e
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
Through rubbing an object has acquired a charge of -1 nanoCoulomb.
electrons have been transferred to the object
A current in a long, straight wire produces a magnetic field. The magnetic field lines
form circles that go around the wire.
Make a prediction. When we connect the power supply, the wire will move
forward
A and B represent objects with -2 and +1 unit of charge respectively. Choose the pair of force vectors that correctly compare the electric force on A (caused by B) with the electric force on B (caused by A).
b
A wire carries a steady current of 30.0 A. What total charge (in C) passes through a cross-sectional area of the wire in a 20.0 s time interval?
Steady Current Flow = Total Charge C/ Time 30 A= C/20s so C=30A*20s Answer 600 C
In a storm, falling raindrops carry a current density of +1.0*10-5 A/m2 towards the ground. If 1000 drops strike each square meter of ground per second, calculate the magnitude and sign of the average charge on each raindrop in Coulomb.
+1.0 *10^-8
.Suppose that a picture of electric field lines is drawn following the convention that 2 field lines emerge from a small sphere with 2 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 (link to photo) https://utk.instructure.com/assessment_questions/466998/files/718135/download?verifier=QouHEUWBS2xTV5zcReVt7DyYfodhxAlBYkqRP7Em
+4 pc
The red charge on the left is a positive 1 microCoulomb charge. What is the magnitude and sign of the blue charge on the right?
-2.6 microCoulomb
What do you already know about the electrostatic force that can exist between two interacting objects? Pick the correct statements from the choices below.
-It depends on the net charge of each of the interacting objects. -it can be attractive -it can be repulsive
What do you know already about atoms, elementary particles, and charges? Select multiple answers!
-Protons and electrons have charges qe and -qe, respectively, where qe is the smallest quantum of charge. -Electrically neutral materials contain the same number of protons and electrons. -Neutral objects become negatively charged by acquiring additional electrons from other objects.
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? (link to photo) https://utk.instructure.com/assessment_questions/467246/files/718360/download?verifier=BxWG7pO5EPPpd4lcpnOXP8hmJ5Tu0hbWjxm2rj1N
0
Point P is at a perpendicular distance x from each wire carry current I in the directions indicated. What is the magnetic field B at point P? (link to photo) https://utk.instructure.com/assessment_questions/467166/files/718259/download?verifier=PHiJ05APxNm0Ra6Rg16pbBRilXY0n4qVv3kegTKp
0
What is the force (magnitude and direction) on a -1 μC charge located at the origin from a -5 μC charge at x = 5 m?
0.0018 N into negative x-direction
What is the electrostatic potential energy of a -5μC charge located at x = 5 m and a -2 μC charge located at the origin?
0.018 J
In the figure below, 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? (link to photo) https://utk.instructure.com/assessment_questions/467245/files/718359/download?verifier=ePcXBz0N4gpfoP6MUb13DGfXOEjRBMR0WEpT6lx2
0.057 N
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?
0.17Nm
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? (link to photo) https://utk.instructure.com/assessment_questions/467301/files/718400/download?verifier=ZsgbwU9cKnkoGNiZir0KxRkHyxpuqVYzvOxhJdtl
0A
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 compass shows the correct direction of the magnet field at point A? (link to photo) https://utk.instructure.com/assessment_questions/467162/files/718255/download?verifier=HFtJB1XT1r0lYp9jfciFqKFoxtRoEfZ25z7WSg7a
1
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.
Consider the 5 arrangements of charges below. (Electric Field Hockey Simulation) Which of the following statements is true? 1) All of the pucks feel a force to the right. 2) The puck in C feels a greater force to the right than the puck in D. 3) The puck in E feels a force to the right that is four times greater than that felt by the puck in B. 4) The net force on the puck in A is zero. 5) The puck in E feels a force to the right that is four times greater than that felt by the puck in D. (link to photo) https://utk.instructure.com/assessment_questions/467293/files/718397/download?verifier=Dz794JuqJcU999NPr65oxHNkKTUMwUuQ10AVNiq6
1 and 3 only
Which of the points shown in the figure below are at the same potential? (link to photo) https://utk.instructure.com/assessment_questions/467005/files/718145/download?verifier=ydA4xjYOtuiJ8BblmWJH2nMigJxgeDEpQqUsgusq
1 and 4
Which of the points shown in the figure below are at the same potential? (link to photo) https://utk.instructure.com/assessment_questions/467237/files/718356/download?verifier=wZ52FDiQuXJUzUWvYInAoJRhHBvjLAzrzbglCk2Y
1 and 4
Two 10 μC charges are located at (x, y) = (0, 3m) and (3 m, 0), respectively. What is the magnitude of the force on the 1 μC charge at the origin?
1.41*10-2 N
What is the capacitance of the series RC circuit referred to in the previous problem?
100 microFarad
What is the resistance of the series RC circuit referred to in the previous problem?
10000 Ω
Determine the equivalent resistance between points A and B in the following circuit. (link to photo) https://utk.instructure.com/assessment_questions/467156/files/718244/download?verifier=POHesnU2FAl7cDba0wN79FVCQ4NHVcQKdt1uqQc0
15 kΩ
Which statement is false? 1. There is no net force acting on either loop. 2. There is no torque acting on loop A but a torque is acting on loop B. 3. Loop A has lower potential energy than loop B. 4. Loop A is in stable equilibrium and loop B is in unstable equilibrium.
2. There is no torque acting on loop A but a torque is acting on loop B.
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?
2.6 MJ
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
What is the time constant for the discharge of this capacitor? (link to photo) https://utk.instructure.com/assessment_questions/467157/files/718245/download?verifier=4C4J1MK31anpBmPznpvtCC6yBvCbUDxMXbRCOKbh
4 s
What is the equivalent resistance between the points A and B?
4.3Ω
The immediate cause of many deaths is ventricular fibrillation, an uncoordinated quivering of the heart as opposed to proper beating. An electric current discharged to the chest can cause momentary paralysis of the heart muscle, after which the heart will sometimes start organized beating again. A defibrillator is a device that applies a strong electric shock to the chest over a time interval of a few milliseconds. Assume that an energy of 300 J is to be delivered from the defibrillator, having a 30.0 microFarad capacitance. To what potential difference must the defibrillator be charged?
4472 V
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?
4F
The figure below shows different ways to connect a light bulb to a battery with wires. Which of the bulbs will light up? (link to photo) https://utk.instructure.com/assessment_questions/467012/files/718150/download?verifier=3FvbMBedstB66mqbvuTcGsoDD0ZSZ4aI0EVFlGPy
5
Two uniformly charged spheres are firmly fastened to and electrically insulated from frictionless pucks on an air table. The charge on sphere 2 is three times the charge on sphere 1. Which force diagram correctly shows the magnitude and direction of the electrostatic forces? (link to photo) https://utk.instructure.com/assessment_questions/467141/files/718223/download?verifier=9BlP9OGsxRsLXnw5el5MjsMlxdenEWnfDq540Kyf
5
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?
5.3*10^-9 m
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 2 μC charge at the origin?
6*104 V
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? (link to photo) https://utk.instructure.com/assessment_questions/467234/files/718355/download?verifier=81xMpy1ArsEu90xq7FCr9B2qjzawCHssx3PZ3Ozo
8 microCoulomb
Two 1 microCoulomb charges are 2.9 m apart. How much energy (in milliJoule) went into assembling these two charges?
9e^9*((1e^-6)^2/2.9) = 0.003103448 J = 3.1 milliJoule
The region of space around a moving proton contains
both an electric and a magnetic field.
Rank in order, from brightest to dimmest, the identical bulbs A to D.
A>B>C=D
Find the current I (in A) in a long straight wire that would produce a magnetic of 2.0*10-4 T at a distance of 3.25 cm from the wire.
Apply B = μoI/2πr (2.0*10^-4)= (4π X 10-7)(I)/ (2π(0.0325) so (2π(0.0325)((2.0*10^-4)/ (4π X 10-7) =I = 32.5
How should the field lines inside this bar magnet be drawn?
Approximately parallel from the South pole to the North pole.
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. (link to photo) https://utk.instructure.com/assessment_questions/467233/files/718354/download?verifier=VyBFAeXJQMgdEkn0BXKs4DHs9lcLtTayrsm76LYD
B > A > C > (D =0)
Four arrangements of charge are shown. Each charge has the same magnitude, but some are positive (+) and some are negative (-). All distances are to the same scale. In which arrangement would the magnitude of the force felt by a positive test charge placed at P be the largest?
B and D
A diagram of an irregularly shaped charged conductor is shown below. Four locations along the surface are labeled A, B, C, and D. Rank these locations in increasing order of the strength of the electric field just outside the surface, beginning with the smallest electric field
B<C<D<A
Two balls rest on a frictionless surface. One ball is given a charge of +Q. The other ball is given a charge of +3Q. Which diagram best represents the magnitude and direction of the force vectors on the balls? (link to photo) https://utk.instructure.com/assessment_questions/467142/files/718224/download?verifier=zHDpj9rORl98HfWQsSqBcfvEjpQZVgxN8TaCTbWv
C
The SI unit of capacitance is Farad (F). This is the same as
C/V
Which requires the most positive work done by an external force, to move a positive point charge from point P to point 1, 2, 3, or 4? All those points are the same distance from P.
P-->1
Which requires zero work, to move a positive point charge from point P to point 1, 2, 3, or 4? All those points are the same distance from P.
P-->3
Two cylindrical copper wires have the same mass. Wire A is 4 times as long as wire B. How are their resistances are related?
RA = 16RB
Which of the charge configurations depicted would give rise to the potential shown below? (link to photo) https://utk.instructure.com/assessment_questions/467148/files/718231/download?verifier=9NXAHkmzkPs2wQLwZ9yA20yhwtEaLnI5pxFrwbr4
E The potential is positive very close to a positive charge and negative very close to a negative charge.
A cube with sides of area 24 cm2 contains a 48.1 nanoCoulomb charge. Find the flux of the electric field through the surface of the cube in units of Nm2/C.
E = Q/0 (48.1 x 10^-9 C) / (8.85 x 10^-12 c^2/Nm^2) = 5435.028 Nm^2/C
A 64 microCoulomb charge is located at the origin and a -48 microCoulomb charge is located on the y-axis at y = 57 cm. What is the magnitude of the force with which the charges attract each other in units of N?
F=(kq1q2)/r^2 k=9x10^9 F= [(9x10^9)(93x10^-6)(-28x10^-6)]/(0.448^2) = -116.768 = 116.77
A capacitor with a charge of 3.3 C has its terminals shorted by a metal wire so that the charge flows off within 1.3 s. What is the average current flowing during that time in Ampere (A)?
I = delta q / delta t Average current flow = change in Q/change in t Average current flow = 3.3 C / 1.3s Average current flow = 2.54 A
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. (link to photo) https://utk.instructure.com/assessment_questions/467238/files/718357/download?verifier=bottcqK4OSkoo3N0SqDzAcU8iRe7p0Up5FH25QJJ
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 Q1and 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. (link to photo) https://utk.instructure.com/assessment_questions/466996/files/718134/download?verifier=pLUCOnXwegJJBrtvfgsnLLUiMEoYOiotW7IRsxJn
II and IV are correct
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
Assume that the potential difference between the positive and negative plate is 100 V. A proton travels from the positive to the negative plate.
Its kinetic energy increases by 1.6*10-17 J = 100 eV.
Are all the diagrams below valid field line diagrams?
Only diagram d is not valid.
Two point charges with 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?
The +x direction
What do you think will happen when a negatively charged balloon is moved towards the neutral wall?
The balloon will be attracted to the wall.
Equipotential lines around several point charges are shown. What are the signs of the charges at points A and B? (link to photo) https://utk.instructure.com/assessment_questions/467149/files/718232/download?verifier=nU89W99COKi9QitutxpQ544QgMLh2jPRy0V1GO1h
The charge at B is positive and the charge at A is negative.
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?
The field exerts a force on wire #2 (directed right).
Clothes taken from a clothes dryer sometimes cling together. Consider a load of wool socks and cotton-polyester shirts
The socks will cling to the shirts, but not to each other.
A bird sits on a high-voltage line. Why does the bird not get hurt?
The whole bird is at approximately the same potential, so there is no electric field across it.
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
Two 3.1 microCoulomb charges are 1.1 m apart. What is the potential at each charge due to the other in V?
[(9e^9)(3.1e^-6)]/1.1 = 25364 V
Which one of the following best illustrates magnetic field lines associated with the bar magnets shown? (link to photo) https://utk.instructure.com/assessment_questions/467248/files/718362/download?verifier=zl5O0ZMIB00y2rvP9euY4P8nrgXE5JRjiIvJLJun
a
Which of the following statements are true about the electric potential or the electric potential difference? (a) The SI unit of the electric potential is volts (V). (b) The electric potential can also be expressed in units of Joules. (c) The electric potential produced by a charge at a given location provides a measure of the rate at which charge flows past that point. (d) As a positive charge moves in the direction of an electric field, it gains electric potential. (f) The electric potential difference between two points is the difference in potential energy possessed by another charge at those two points, divided by this charge.
a and f only
Which of the following are true of static charges on everyday objects? (a) Like charges repel. (b) Like charges attract. (c) Opposite charges repel. (d) Opposite charges attract. (e) A positively charged object has lost electrons. (f) A positively charged object has gained protons. (g) A negatively charged object has lost protons. (h) A negatively charged object has gained electrons.
a, d, e, h only
Which of the following statements about a conductor in electrostatic equilibrium is false? -The electric field inside the conductor is zero. - Just outside the conductor, the electrostatic field is perpendicular to its surface. -The net charge inside the conductor is zero, all excess charge resides on the surface. -A charge located within a hole in a conductor at equilibrium feels no force from charges outside the conductor. -All the above statements are true.
all of the above statements are true
A certain physics textbook shows a region of space in which two electric field lines cross each other. We should conclude that
author of textbook made a mistake
The track ABC in the figure is a reproduction of the path of a charged particle in a cloud chamber. If the magnetic field is perpendicular to this sheet of paper and directed into the paper, the particle
has a negative charge and has moved from C to A.
An electron travels through free space from point A, which is at 100 V, to point B, which is at 200 V. The kinetic energy of the electron during this trip
increases by 1.6*10-17 J.
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? (link to photo) https://utk.instructure.com/assessment_questions/467018/files/718159/download?verifier=j3kzRXxvoweyToXG5SLPSNmt1tHZFD5ODXtomQDX
into the page
An electron moves perpendicular to a magnetic field. A magnetic force acts on it in the direction shown. What is the direction of B?
into the page
Consider a uniform electric field, for example the field inside a parallel plate capacitor, as shown. If an electron is taken from location A to location B to location C, how does its potential energy change?
it increases
Compared to the effective resistance of two resistors connected in series, the effective resistance of the same two resistors connected in parallel is
lower
When a positive charge is released from rest in a uniform electric field, it will
move with constant acceleration
Compare the electric flux through surfaces (a) and (b). All charges have magnitude q.
none of the above
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
Choose the force vector that correctly shows the direction o f t h e net force on charge B due to the other two charges. Charge is given in arbitrary units.
none of these, the vector should point up and left.
The paths of several particle moving through a region with a magnetic field pointing into the page are shown. Which particles are positively charged? (link to photo) https://utk.instructure.com/assessment_questions/467164/files/718258/download?verifier=6pGfSSuIHiESbop9e27PfO2lmH3a6YVe2s16xzrC
particles 1 and 5
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 (link to photo) https://utk.instructure.com/assessment_questions/467247/files/718361/download?verifier=cwcXoqKyT5CkbTd61xVRAXGL7j3sNEjMBmgtTNq4
points in the positive z-direction
A solid, conducting sphere of radius R is positively charged. Of the following distances from the center of the sphere, which location will have the greatest electric potential? (Take V = 0 at r = infinity.)
r=0 (center of the sphere)
A cosmic ray electron (m = 9.1*10-31 kg) moves at 7.16*106 m/s perpendicular to the Earth's magnetic field at an altitude where field strength is 1.13*10-5 T. What is the radius r (in m) of the circular path the electron follows?
r=mv/qB m= (9.1*10^-31kg) v=(7.16*10^6 m/s) q=(1.6*10^-19) B=(1.13*10^-5) so r= (9.1*10^-31kg)(7.16*10^6 m/s) / (1.6*10^-19)(1.13*10^-5) =3.60m
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 (link to photo) https://utk.instructure.com/assessment_questions/467304/files/718403/download?verifier=l504sPoKWFNzCv28SXI9XQyEH9bwpQ0JHUV1Ly72
the charge is negative and slowing down
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? (link to photo) https://utk.instructure.com/assessment_questions/467022/files/718162/download?verifier=n7atf41suonK084TRImTVWuHggAe4QjgthP5KmjW
the magnetic force on the wire points towards the left
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 (link to the photo) https://utk.instructure.com/assessment_questions/467019/files/718160/download?verifier=4UWpiRSBm83Cbqo0XmWnqcTs7ouLT6JXtTw8eR4W
the magnetic force will be zero
What is the direction of the magnetic force on the wire segment cd? (link to photo) https://utk.instructure.com/assessment_questions/467163/files/718256/download?verifier=WgyMTLCZ69MIUSTDbRWnkTsnOejusardLTVDdX8C
the negative z-direction
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
Make a prediction! When we connect the power supply, the magnet will
turn (north pole towards coil) and be attracted.
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?
up
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
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
zero
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. The flux lines exhibit convergence and there are no flux lines passing through any other face. If the magnitude of the electric field at the centre of the cube is E, the total charge inside the cube is (link to photo) https://utk.instructure.com/assessment_questions/467290/files/718396/download?verifier=XoKsjVq4Bev7lp0RvozslRwaZnaiuKlZqwlQnDAu
zero
Location P is equidistant from the two charges of an electric dipole. The voltage at P is
zero
The flux of water through this spherical volume is
zero
If electrical energy costs $0.10 for each kWh, what would it cost to raise a house of mass 5*105 kg (500 metric tons) a height of 1 m above the ground, using an electric motor of 50% efficiency? Use g = 10 m/s2.
~$0.28
The graph below shows a contour map of the equipotential surfaces due to 3 point charges. point P.
~800 V/m down
