Induction

If the total energy of a harmonic oscillator is reduced by 1/3, what is the change in the amplitude of the oscillations? A) 1/3 B) 3 C) 3 D) 1/3

A) 1/3

The zirconium nucleus contains 40 protons, and an electron is 1.0 nm from the nucleus. What is the electric force on the electron due to the nucleus? ( e = 1.60 × 10-19 C, k = 1/4!"0 = 9.0 × 109 N ∙ m2/C2) A) 9.2 nN B) 6.8 nN C) 3.7 nN D) 2.9 nN E) 1000 C

A) 9.2 nN

Four point charges of equal magnitudes but with varying signs are arranged on three of the corners and at the center of the square of side d as shown in Figure 19-2. Which of the arrows shown represents the net force acting on the center charge? A) A B) B C) C D) D E) none of the above

A) A

Which of the arrows shown in Figure 19-12 represents the correct direction of the electric field between the two metal plates? A) A B) B C) C D) D E) none of the above

A) A

Four waves are described by the following expressions, where distances are measured in meters and times in seconds. I y = 0.12 cos(3x - 21t) II y = 0.15 sin(6x + 42t) III y = 0.13 cos(6x + 21t) IV y = -0.23 sin(3x - 42t) Which of these waves have the same speed? A) II and IV B) III and IV C) II and III D) I and III E) I and II

A) II and IV

The aurora is caused when electrons and protons, moving in the earth's magnetic field of ≈5.0×10−5T, collide with molecules of the atmosphere and cause them to glow. Part A What is the radius of the circular orbit for an electron with speed 1.0×106 m/s ? Part B What is the radius of the circular orbit for a proton with speed 6.0×104 m/s ?

11 cm 12.5 m

A charged particle is observed traveling in a circular path of radius R in a uniform magnetic field. If the particle was traveling twice as fast, the radius of the circular path would be 4R. R/4. 2R. R/2. 8R.

2R.

A very long straight current-carrying wire produces a magnetic field of 20 mT at a distance d from the wire. To measure a field of 5 mT due to this wire, you would have to go to a distance from the wire of d2√. 4d. 2d. 8d. 16d.

4d.

The magnetic field 10 cm from a wire carrying a 1 A current is 2 μT. Part A What is the field 4 cm from the wire?

5 ut

For a proton moving in the direction of the electric field A) its potential energy decreases and its electric potential decreases. B) its potential energy increases and its electric potential increases. C) its potential energy increases and its electric potential decreases. D) its potential energy decreases and its electric potential increases. E) both its potential energy and it electric potential remain constant

A) its potential energy decreases and its electric potential decreases.

A charged particle that is moving in a static uniform magnetic field A) may experience a magnetic force, but its speed will not change. B) may experience a magnetic force which will cause its speed to change. C) will always experience a magnetic force, regardless of its direction of motion. D) may experience a magnetic force, but its direction of motion will not change. E) None of the above statements are true.

A) may experience a magnetic force, but its speed will not change.

Water flows through a pipe. The diameter of the pipe at point B is larger than at point A. Where is the speed of the water greater? A) point A B) point B C) same at both A and B D) Cannot be determined from the information given.

A) point A

Four charged particles (two having a charge +Q and two having a charge -Q) are arranged in the xy-plane, as shown in the figure. These particles are all equidistant from the origin. The electric potential (relative to infinity) at point P on the z-axis due to these particles, is A) zero. B) positive. C) negative. D) impossible to determine based on the information given.

A) zero.

These charged particles are traveling in circular orbits with velocities and field directions as noted. Which particles have a negative charge?

A, C. The force to produce these circular orbits is directed toward the center of the circle. Using the right-hand rule for forces, we see that this will be true for the situations in A and C if the particles are negatively charged.

A coil of wire containing N turns is in an external magnetic field that is perpendicular to the plane of the coil and it steadily changing. Under these circumstances, an emf ε is induced in the coil. If the rate of change of the magnetic field and the number of turns in the coil are now doubled (but nothing else changes), what will be the induced emf in the coil? A. 4ε B. ε C. ε/2 D. ε/4 E. 2ε

A. 4ε

An unmagnetized metal sphere hangs by a thread. When the north pole of a bar magnet is brought near, the sphere is strongly attracted to the magnet, as shown in Figure Q24.29. Then the magnet is reversed and its south pole is brought near the sphere. How does the sphere respond? A. It is strongly attracted to the magnet. B. It is weakly attracted to the magnet. C. It does not respond. D. It is weakly repelled by the magnet. E. It is strongly repelled by the magnet

A. It is strongly attracted to the magnet.

The wire in the figure carries a current I that is decreasing with time at a constant rate. The wire and the three loops are all in the same plane. What is true about the currents induced in each of the three loops shown? A. Loop A has counterclockwise current, loop B has no induced current, and loop C has clockwise current. B. No current is induced in any loop. C. Loop A has clockwise current, loop B has no induced current, and loop C has counterclockwise current. D. The currents are clockwise in all three loops. E. The currents are counterclockwise in all three loops.

A. Loop A has counterclockwise current, loop B has no induced current, and loop C has clockwise current.

A coil lies flat on a tabletop in a region where the magnetic field vector points straight up. The magnetic field vanishes suddenly. When viewed from above, what is the sense of the induced current in this coil as the field fades? A. The induced current flows counterclockwise. B. There is no induced current in this coil. C. The induced current flows clockwise. D. The current flows clockwise initially, and then it flows counterclockwise before stopping.

A. The induced current flows counterclockwise.

The figure shows an edge view of a current loop. Using what you've learned in Figure 24.15, which arrow gives the direction of the field in the center of the loop?

A. Using the right-hand rule for currents on any part of the loop shows that the field at the center of the loop is directed toward the top of the page.

A long straight wire lies on a horizontal table and carries an ever-increasing current toward the north. Two coils of wire lie flat on the table, one on either side of the wire. When viewed from above, the direction of the induced current in these coils is A. clockwise in the east coil and counterclockwise in the west coil. B. counterclockwise in the east coil and clockwise in the west coil. C. clockwise in both coils. D. counterclockwise in both coils.

A. counterclockwise in the east coil and clockwise in the west coil.

The small currents in axons corresponding to nerve impulses produce measurable magnetic fields. A typical axon carries a peak current of 0.040 μA. Part A What is the strength of the field at a distance of 2.3 mm ?

B = 3.5×10−12 T

A long straight horizontal wire carries a current I = 5.00 A to the left. A positive 1.00 C charge moves to the right at a distance 2.00 m above the wire at constant speed v = 4500 m/s . (Figure 1) What is the magnitude B of the magnetic field at the location of the charge due to the current-carrying wire? What is the magnitude F of the magnetic force on the charge?

B = 5.00×10−7 T F = 2.25×10−3 N

A flat circular loop of radius 0.10 m is rotating in a uniform magnetic field of 0.20 T. Find the magnetic flux through the loop when the plane of the loop and the magnetic field vector are parallel. A) 3.1 × 10-3 T ∙ m2 B) 0 T ∙ m2 C) 6.3 × 10-3 T ∙ m2 D) 5.5 × 10-3 T ∙ m2

B) 0 T ∙ m2

A rigid rectangular loop, which measures 0.30 m by 0.40 m, carries a current of 5.5 A, as shown. A uniform external magnetic field of magnitude 2.9 T in the negative x-direction is present. Segment CD is in the x-z plane and forms a 35° angle with the z-axis, as shown. An external torque applied to the loop keeps it in static equilibrium. The magnitude of the external torque is closest to: A) 1.6 N ∙ m B) 1.1 N ∙ m C) 1.4 N ∙ m D) 0.73 N ∙ m E) 1.3 N ∙ m

B) 1.1 N ∙ m

A 2.0 kg block on a frictionless table is connected to two springs with spring constants k1 and k2 whose opposite ends are fixed to walls, as show in the figure. What is the oscillation angular frequency if k1 = 7.6 N/m and k2 = 5.0 N/m? A) 0.56 rad/s B) 2.5 rad/s C) 0.40 rad/s D) 3.5 rad/s

B) 2.5 rad/s

A 100-kg person sits on a 5-kg bicycle. The weight is borne equally by the two wheels of the bicycle. The tires are inflated to a gauge pressure of 8.0 ×105 Pa and are 2.0 cm wide. What length of each tire is in contact with the ground? A) 6.4 cm B) 3.2 cm C) 1.8 cm D) 1.6 cm E) 2.4 cm

B) 3.2 cm

The U-tube shown in Figure 15-3 contains mercury with a density of 13,600 kg/m3. It is open on one end and the other end is connected to a boiler, which contains water at high pressure. The water from the boiler pushes directly on the mercury column. What is the gauge pressure at point A in the boiler? The density of water is 1,000 kg/m3. A) 441 Pa B) 4.41 kPa C) 128 Pa D) 4.54 kPa E) 449 Pa

B) 4.41 kPa

The primary coil of a transformer has 100 turns and its secondary coil has 400 turns. If the ac voltage applied to the primary coil is 120 V, what voltage is present in its secondary coil? A) 30 V B) 480 V C) 400 V D) 100 V E) 70 V

B) 480 V

A simple harmonic oscillator is undergoing oscillations with an amplitude A. How far is it from its equilibrium position when the kinetic and potential energies are equal? A) A/sqrt 3 B) A/sqrt 2 C) A D) A/2 E) A/3

B) A/sqrt 2

Which one of the following is a correct statement for a number of resistors connected in series or parallel? A) The flow of current is different through resistors connected in a series circuit. B) The total resistance in a parallel circuit decreases as more resistors are added. C) The total resistance in a series circuit decreases as more resistors are added. D) The voltage is different across resistors connected in a parallel circuit. E) None of the above statements is correct.

B) The total resistance in a parallel circuit decreases as more resistors are added.

A coil lies flat on a level tabletop in a region where the magnetic field vector points straight up. The magnetic field suddenly grows stronger. When viewed from above, what is the direction of the induced current in this coil as the field increases? A) clockwise initially, then counterclockwise before stopping B) clockwise C) counterclockwise D) There is no induced current in this coil.

B) clockwise

A person stands between two speakers driven by the same source. Each speaker produces a tone with a frequency of 200 Hz on a day when the speed of sound is 330 m/s. The person is 1.65 m from one speaker and 4.95 m from the other. What type of interference does the person perceive? A) destructive B) constructive C) both constructive and destructive D) neither constructive nor destructive

B) constructive

A bar magnet is oriented above a copper ring, as shown in the figure. If the magnet is pulled upward, what is the direction of the current induced in the ring, as viewed from above? A) There is no current in the ring. B) counterclockwise C) clockwise

B) counterclockwise

If you were to cut a small permanent bar magnet in half, A) neither piece would be magnetic. B) each piece would in itself be a smaller bar magnet with both north and south poles. C) one piece would be a magnetic north pole and the other piece would be a south pole. D) None of these statements is true.

B) each piece would in itself be a smaller bar magnet with both north and south poles.

As shown in the figure, two parallel wires carry a current I in opposite directions, and this current is decreasing. A rectangular loop is centered between the wires. The direction of the induced current through the resistor R is A) from a to b. B) from b to a. C) No current is induced.

B) from b to a

In simple harmonic motion, the speed is greatest at that point in the cycle when A) the magnitude of the acceleration is a maximum. B) the magnitude of the acceleration is a minimum. C) the kinetic energy is a minimum. D) the potential energy is a maximum. E) the displacement is a maximum.

B) the magnitude of the acceleration is a minimum.

The reason that you do not observe a Doppler shift when you listen to the car radio while driving is that A) the air inside the car is moving at the same speed as the car. B) the source and observer are moving at the same speed. C) the speed of the car is too slow compared to the speed of sound. D) there is a Doppler shift but we don't notice it. E) the speed of the car is too fast compared to the speed of sound.

B) the source and observer are moving at the same speed.

A chain of paper clips is hung from a permanent magnet. Which diagram shows the correct induced pole structure of the paper clips?

B. All of the induced dipoles will be aligned with the field of the bar magnet.

Which way will this current loop rotate? A. Clockwise. B. Counterclockwise. C. The loop will not rotate.

B. Looking at the forces on the top and the bottom of the loop, we can see that the loop will rotate counterclockwise. Alternatively, we can look at the dipole structure of the loop: With a north pole on the left and a south pole on the right, the loop will rotate counterclockwise.

The three loops of wire shown in the figure are all hanging in the same uniform magnetic field B⃗ that is perpendicular to the page and does not vary with time. Loop 1 swings back and forth like the bob in a pendulum, Loop 2 rotates about a vertical axis, and Loop 3 oscillates up and down at the end of a spring. Which loop (or loops) will have an emf induced in them? A. Loop 1 B. Loop 2 C. Loop 3 D. Loops 2 and 3 E. Loops 1 and 3

B. Loop 2

An outer metal ring surrounds an inner metal ring, as shown in the figure. The current in the outer ring is counterclockwise and decreasing. What is the direction of the induced current in the inner ring? A. clockwise B. counterclockwise C. There is no induced current in the inner ring.

B. counterclockwise

The magnitude of a magnetic field a distance 3.0 um from a wire is 20.0 ×10-4 T. How much current is flowing through the wire? Assume the wire is the only contributor to the magnetic field. A) 19 mA B) 377 mA C) 30 mA D) 188 mA

C) 30 mA

An electron is initially at rest. It is accelerated through a potential difference of 400 V. What is the kinetic energy of this electron? The magnitude of the electron charge is e=1.6 x 10-19 C. A) 800 J B) 6400 J C) 6.4 ×10-17 J D) 400 J E) 0 J

C) 6.4 ×10-17 J

Crests of an ocean wave pass a pier every 12.0 s. If the waves are moving at 5.6 m/s, what is the wavelength of the ocean waves? A) 77 m B) 57 m C) 67 m D) 34 m

C) 67 m

Two strings both vibrate at exactly 819 Hz. The tension in one of them is then increased slightly. As a result, six beats per second are heard when both strings vibrate. What is the new frequency of the string that was tightened? A) 816 Hz B) 822 Hz C) 825 Hz D) 813 Hz

C) 825 Hz

Three identical capacitors are connected in parallel to a potential source (battery). If a charge ofQ flows into this combination, how much charge does each capacitor carry? A) Q B) Q/9 C) Q/3 D) 3Q

C) Q/3

A capacitor C is connected in series with a resistor R across a battery and an open switch. If a second capacitor of capacitance 2C is connected in parallel to the first, the time constant of the new RC circuit will be A) twice as large as before. B) one-half as large as before. C) three times a large as before. D) one-fourth as large as before. E) the same as before

C) three times a large as before.

When the current through a resistor is increased by a factor of 4, the power dissipated by it A) increases by a factor of 4. B) decreases by a factor of 16. C) decreases by a factor of 4. D) increases by a factor of 16. E) remain unchanged.

D) increases by a factor of 16.

An investigator has made a solenoid by wrapping 100 turns of wire on a tube that is 10 cm long and 2 cm in diameter. The power supply is providing as much current as it can, but a stronger field is needed, so the solenoid must be re-wrapped. Which of the following will result in a stronger field?

C. If you keep the number of turns of wire the same and decrease the overall length, the field strength will increase. The field doesn't depend on the diameter.

Does the compass needle rotate? A. Yes, clockwise. B. Yes, counterclockwise. C. No, not at all.

C. The compass needle will not rotate, since there is no force between the stationary charges on the rod and the magnetic poles of the compass needle.

Four wires carry currents in the directions shown. A uniform magnetic field is directed into the paper as shown. Which wire experiences a force to the left?

C. The right-hand rule for forces gives the direction of the force. With the field into the paper, the force is to the left if the current is toward the top of the paper

A bar magnet is oriented above a copper ring. if the magnet is kept fixed while the ring is dropped, what is the direction of the current induced in the ring, as viewed from below the ring? A. There is no current in the ring. B. counterclockwise C. clockwise

C. clockwise

A coil lies flat on a horizontal tabletop in a region where the magnetic field points straight down. The magnetic field disappears suddenly. When viewed from above, what is the direction of the induced current in this coil as the field disappears? A. There is no induced current in this coil. B. clockwise initially, then counterclockwise before stopping C. clockwise D. counterclockwise

C. clockwise

An electric dipole in a uniform electric field experiences no net force, but it does experience a net torque. The rotation of this dipole will be ?? Clockwise Counterclockwise

Counterclockwise

A circular conducting loop with a radius of 1.00 m and a small gap filled with a 10.0 # resistor is oriented in the xy-plane. If a magnetic field of 2.0 T, making an angle of 30° with the z-axis, increases to 9.0 T, in 2.0 s, what is the magnitude of the current that will be caused to flow in the conductor? A) 0.095 A B) 0.55 A C) 0.24 A D) 0.95 A

D) 0.95 A

A 200-W light bulb is connected across 110 V. What current will flow through this bulb? A) 0.90 A B) 0.60 A C) 0 A D) 1.8 A E) 0.36 A

D) 1.8 A

A cubical box 25.00 cm on each side is immersed in a fluid. The pressure at the top surface of the box is 109.4 kPa and the pressure on the bottom surface is 112 kPa. What is the density of the fluid? A) 1090 kg/m3 B) 1030 kg/m3 C) 1120 kg/m3 D) 1060 kg/m3 E) 1000 kg/m3

D) 1060 kg/m3

An electron enters a magnetic field of 0.75 T with a velocity perpendicular to the direction of the field. At what frequency does the electron traverse a circular path? (The mass of an electron is 9.1 × 10-31 kg, and the charge of an electron is 1.6 × 10-19 C.) A) 2.1 × 1014 Hz B) 4.8 × 10-7 Hz C) 4.8 × 10-11 Hz D) 2.1 × 1010 Hz

D) 2.1 × 10^10 Hz So by substitution T = 2πm/qB Since period T, is the inverse of the frequency, we have f = qB/2πm Now we can solve for f f = (1.6 X 10-19)(.75)/(2π)(9.1 X 10-31)

A 4-! resistor is connected in parallel with a 12-! resistor and this combination is connected to a DC power supply with voltage V as shown in Figure 21-3. If the total current in this circuit is 2 A, what is the value of voltage V? A) 3 V B) 2 V C) 1.5 V D) 6 V E) None of the other answers is correct.

D) 6 V

Two people are talking at a distance of 3.0 m from where you are and you measure the sound intensity as 1.1 ×10-7 W/m2. Another student is 4.0 m away from the talkers. What sound intensity does the other student measure? A) 7.8 ×10-7 W/m2 B) 8.3 ×10-8 W/m2 C) 1.5 ×10-7 W/m2 D) 6.2 ×10-8 W/m2 E) 2.5 ×10-8 W/m2

D) 6.2 ×10-8 W/m2

A negative charge is moved from point A to point B along an equipotential surface. Which of the following statements is true for this case? A) The negative charge performs work in moving from point A to point B. B) Work is required to move the negative charge from point A to point B. C) Work is both required and performed in moving the negative charge from point A to point B. D) No work is required to move the negative charge from point A to point B.

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

When you are scuba diving, the pressure on your face plate A) is independent of both depth and orientation. B) will be greatest when you are facing upward. C) will be greatest when you are facing downward. D) depends only on your depth, and not on how you are oriented.

D) depends only on your depth, and not on how you are oriented.

When unequal resistors are connected in parallel in a circuit, A) the largest resistance has the largest current through it. B) the same current always runs through each resistor. C) the power generated in each resistor is the same. D) the potential drop is always the same across each resistor.

D) increases by a factor of 16.

A compass is placed above a long wire. When a large current is turned on in the direction shown, in which direction will the compass point?

D. The compass needle will rotate to line up with the field circling the wire. The right-hand rule for fields shows this to be toward the top of the paper in the figure.

The right edge of the circuit in the figure extends into a 50 mT uniform magnetic field. (Figure 1) Part A What is the magnitude of the net force on the circuit? Part B What is the direction of the net force on the circuit?

F = 2.5×10−2 N right

When a current of 2.0 A flows in the 100-turn primary of an ideal transformer, this causes 14 A to flow in the secondary. How many turns are in the secondary? A) 700 B) 114 C) 4 D) 356 E) 14

E) 14

If the ac peak current through a 100 ohm resistor is 1.7 A, the average power dissipated by the resistance is A) 85 W. B) 289 W. C) 170 W. D) 220 W. E) 145 W.

E) 145 W.

A 5.0 !C charge is placed at the 0 cm mark of a meter stick and a -4.0 !C charge is placed at the 50 cm mark. At what point on a line joining the two charges is the electric field zero? A) 2.5 m from the 0 cm mark B) 2.9 m from the 0 cm mark C) 1.4 m from the 0 cm mark D) 3.3 m from the 0 cm mark E) 4.7 m from the 0 cm mark

E) 4.7 m from the 0 cm mark

Electrical and gravitational forces follow similar equations with one main difference: A) Electrical forces attract and gravitational forces repel. B) Gravitational forces obey the inverse square law and electrical forces do not. C) Electrical forces repel and gravitational forces attract. D) Electrical forces obey the inverse square law and gravitational forces do not. E) Gravitational forces are always attractive but electrical forces can be attractive or repulsive.

E) Gravitational forces are always attractive but electrical forces can be attractive or repulsive.

A capacitor consists of a set of two parallel plates of area A separated by a distance d. This capacitor is connected to a battery and charged until its plates carry charges +Q and -Q. If the separation between the plates is doubled, the electrical energy stored in the capacitor will A) be cut in half. B) not change. C) be cut in fourth. D) quadruple. E) double.

E) double.

A uniform 2.5 T magnetic field points to the right. A 3.0-m-long wire, carrying 15 A, is placed at an angle of 30∘ to the field, as shown in the figure.(Figure 1) Part A What is the magnitude of the force on the wire? Part B What is the direction of the force on the wire?

F=56 N into the page

Problem 24.15 The magnetic field of the brain has been measured to be approximately 3.0×10−12T. Although the currents that cause this field are quite complicated, we can get a rough estimate of their size by modeling them as a single circular current loop 16 cm (the width of a typical head) in diameter. Part A What current is needed to produce such a field at the center of the loop?

I = 3.8×10−7 A

Problem 24.19 We have seen that the heart produces a magnetic field, and that this can be used to diagnose problems with the heart. The magnetic field of the heart is a dipole field that is produced by a loop current in the outer layers of the heart. Suppose the field at the center of the heart is 90 pT (a pT is 10−12 T ) and that the heart has a diameter of approximately 12 cm. Part A What current circulates around the heart to produce this field?

I = 8.6×10−6 A

The magnetic field at the center of a 1.2-cm-diameter loop is 2.9 mT . Part A What is the current in the loop? Part B A long straight wire carries the same current you found in part a. At what distance from the wire is the magnetic field 2.9 mT ?

I=28 A L = 1.9×10−3 m

Part A The two 10-cm-long parallel wires in the figure are separated by 5.0 mm. For what value of the resistor R will the force between the two wires be 3.6×10−5 N v=9 R=2 d=5.0mm

R =4.5 Ω

. Right-hand rule for magnetic forces

Spread the fingers of your right hand so that your index finger and thumb point out from your hand. Rotate your hand to point your thumb in the direction of v⃗ and your index finger in the direction of B⃗ . Now point your middle finger so that it is perpendicular to your palm. It will point in the direction of F⃗ .

If the charge were located a distance 4.00 m from the wire, how would the net magnetic force on the charge compare t a distance of 2.00 m? The force would be one-fourth as great. The force would be one-half as great. The force would be the same. The force would be double. The force would be quadruple.

The force would be one-half as great.

The following sketches show a wire carrying a current I in the direction indicated. Which sketch correctly shows the magnetic field lines around the wire?

The magnetic field lines around a current-carrying wire are shown in the figure. In what direction is the current flowing in the wire?

Table 24.1 shows that the strength of the magnetic field 1 cm from a wire carrying a 10 A current is 4 times the earth's field. Referring to At what distance from the wire will the field equal that of the earth?

The strength of the field is inversely proportional to the distance from the wire. If the distance from the wire is increased by a factor of 4, the field strength decreases by a factor of 4.

A circular wire ring is situated above a long straight wire, as shown in the figure. The straight wire has a current I flowing to the right, and this current is increasing at a constant rate. Which of the following statements is true? a. There is an induced current in the wire ring, directed in clockwise orientation. b. There is an induced current in the wire ring, directed in a counterclockwise orientation. c. There is no induced current in the wire ring.

a. There is an induced current in the wire ring, directed in clockwise orientation.

A compass is placed next to a bar magnet as shown. Which figure shows the correct alignment of the compass?

both horizontal, but opposite coloring

A circular coil of copper wire is lying flat on a horizontal table. A bar magnet is held above the center of the coil with its south pole downward. The magnet is released from rest and falls toward the coil. As viewed from above, what is the direction of the current induced in the coil as the magnet approaches the coil? counterclockwise clockwise No current is induced in the coil. An emf but no current is induced in the coil.

clockwise

A single current-carrying circular loop of radius R is placed next to a long, straight wire, as shown in the figure. The current I in the wire flows to the right. In which direction must current flow in the loop to produce a net magnetic field of zero at its center? clockwise counterclockwise It could be either clockwise or counterclockwise. The current in the loop should be zero.

clockwise

What is the direction of the magnetic field at the location of the charge due to the current-carrying wire? (v is to the right and I is to the left) to the left to the right upward downward into the page out of the page

into the page

Problem 24.5 Two wires carry equal currents in opposite directions, as in (Figure 1) . The field is 2.0 mT at a point below the lower wire. The distance between the wires is twice the distance between this point and the lower wire Part A What is the direction of the field at point 1 (midway between the two wires)? Part B What is the strength of the field at point 1? Part C What is the direction of the field at point 2 (the same distance above the upper wire as the 2.0 mT point is below the lower wire) Part D What is the strength of the field at point 2?

into the page B = 6.0 mT out of the page B = 2.0 mT

A rectangular coil, with corners labeled ABCD, has length L and width w. It is placed between the poles of a magnet, as shown in the figure. If there is a current I flowing through this coil in the direction shown, what is the direction of the force acting on section CD of this coil? in the direction of the magnetic field perpendicular to and into the page in the opposite direction of the magnetic field perpendicular to and out of the page The force is zero.

perpendicular to and out of the page

The fact that the magnetic field generates a force perpendicular to the instantaneous velocity of the particle has implications for the work that the field does on the particle. As a consequence, if only the magnetic field acts on the particle, its kinetic energy will ____________. increase over time decrease over time remain constant oscillate

remain constant

A vertical wire carries a current vertically downward. To the east of this wire, the magnetic field points north east south down

south

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

the current is perpendicular to the magnetic field lines.

Select the source(s) responsible for the magnetic field that exerts a force on the moving charge? the charge the current-carrying wire the charge and the current-carrying wire

the current-carrying wire

A long, straight, horizontal wire carries current toward the east. A proton moves toward the east alongside and just south of the wire. What is the direction of the magnetic force on the proton? downward toward the south upward toward the east. toward the north

toward the north

If the resulting trajectory of the charged particle is a circle, what is ω, the angular frequency of the circular motion? Express ω in terms of q, m, and B0.

ω = qB0/m

At a given moment the particle is moving in the +x direction (and the magnetic field is always in the +z direction). If q is positive, what is the direction of the force on the particle due to the magnetic field? + x direction −x direction + y direction −y direction + z direction − z direction This force will cause the path of the particle to curve. Therefore, at a later time, the direction of the force will ____________.

−y direction remain perpendicular to the direction of motion