A coil is wrapped with 340 turns of wire on the perimeter of a circular frame (radius = 8.1 cm) . Each turn has the same area, equal to that of the frame. A uniform magnetic field is turned on perpendicular to the plane of the coil. This field changes at a constant rate from 20 to 80 mT in a time of 20 ms. What is the magnitude of the induced emf in the coil at the instant the magnetic field has a magnitude of 50 mT?

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1. 21 V

2. 18 V

3. 17 V

4. 24 V

5. 37 V

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1. 1.9 A

2. 50 mA

3. 0.26 A

4. 1.5 A

5. zero

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1. 4.2 mV

2. 17 mV

3. 10 mV

4. 2.6 mV

5. 0.21 V

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1. 6.0 mV

2. 5.4 mV

3. 7.9 mV

4. 3.9 mV

5. 14 mV

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1. 36 mA

2. 12 mA

3. 0.18 mA

4. 7.0 mA

5. 65 mA

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1. 66 mV

2. 48 mV

3. 30 mV

4. 76 mV

5. 45 mV

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1. 2.

3.

4. 5.

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1. - 7.1 V

2. + 7.1 V

3. - 4.0 V

4. + 4.0 V

5. - 19 V

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1. 19 mV

2. 22 mV

3. 27 mV

4. 26 mV

5. zero

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1. 1.9 V

2. 2.8 V

3. 1.1 V

4. 2.3 V

5. 1.5 V

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1. 2.

3.

4. 5.

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1. 0.32 A

2. 0.40 A

3. 0.26 A

4. 0.25 A

5. 0.36 A

A conducting rod (length = 2.0 m) spins at a constant rate of 1.8 revolutions per second about an axis that is perpendicular to the rod and through its center. A uniform magnetic field (magnitude = 6.8 mT) is directed perpendicularly to the plane of rotation. What is the magnitude of the potential difference between the center of the rod and either of its ends?

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1. 38 mV

2. 77 mV

3. 25 mV

4. 2.8 mV

5. 0.81 mV

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1. 0.45 mV

2. 0.66 mV

3. 0.16 mV

4. 0.63 mV

5. 0.89 mV

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1. - 0.29 mV

2. + 0.29 mV

3. - 0.51 mV

4. + 0.51 mV

5. - 0.39 mV

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1. 0.53 N to the left

2. 0.53 N to the right

3. 0.76 N to the left

4. 0.76 N to the right

5. None of the above

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1. + 6.9 mV

2. - 6.9 mV

3. - 11 mV

4. + 11 mV

5. - 14 mV

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1. 2.

3.

4. 5.

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1. 0.50 A/s

2. 0.31 A/s

3. 0.74 A/s

4. 0.46 A/s

5. 0.28 A/s

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1. 19 V

2. 3.1 V

3. 6.2 V

4. 14 V

5. 7.8 V

When will the magnetic flux through a loop perpendicular to a uniform magnetic field change?

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1. if the loop is replaced by two loops, each of which has half of the area of the original loop

2. if the loop moves at constant velocity while remaining perpendicular to and within the uniform magnetic field

3. if the loop moves at constant velocity in a direction parallel to the axis of the loop while remaining in the uniform magnetic field

4. if the loop is rotated through 180 degrees about an axis through its center and in the plane of the loop

5. in none of the above cases

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1. No current will be induced in coil 2.

2. DC current (current flow in only one direction) will be induced in coil 2.

3. AC current (current flow in alternating directions) will be induced in coil 2.

4. DC current will be induced in coil 2, but its direction will depend on the initial direction of flow of current in coil 1.

5. Both AC and DC current will be induced in coil 2.

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1. The current in the loop always flows in a clockwise direction.

2. The current in the loop always flows in a counterclockwise direction.

3. The current in the loop flows first in a counterclockwise, then in a clockwise direction.

4. The current in the loop flows first in a clockwise, then in a counterclockwise direction.

5. No current flows in the loop because both ends of the magnet move through the loop.

The alternating currents in power lines usually cannot produce significant electrical currents in human brains. Why not?

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1. 2.

3.

4. 5.

What is the correct form of Ampere's law for circuits with gaps in them?

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1. 2.

3.

4.

5.

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1. 2.

3.

4. 5.

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1. bulb 1 glows more brightly

2. bulb 2 glows more brightly

3. both bulbs glow equally brightly

4. bulb 1 goes out

5. bulb 2 goes out

A circular loop of wire is held in a uniform magnetic field, with the plane of the loop perpendicular to the field lines. Which of the following will not cause a current to be induced in the loop?

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1. Crushing the loop.

2. Rotating the loop about an axis perpendicular to the field lines.

3. Keeping the orientation of the loop fixed and moving it along the field lines.

4. Pulling the loop out of the field.

Suppose you would like to steal power for your home from the electric company by placing a loop of wire near a transmission cable, so as to induce an emf in the loop (an illegal procedure). What should you do?

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1. Place your loop so that the transmission cable passes through your loop.

2. Simply place your loop near the transmission cable.

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1. 2. 3. 4.

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1. inserting the magnet

2. pulling the magnet out

In a region of space, the magnetic field increases at a constant rate. This changing magnetic field induces an electric field that _____.

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1. increases in time

2. is conservative

3. is in the direction of the magnetic field

4. has a constant magnitude