Quiz 6

1) The SI unit of the magnetic flux is

A) T/Vm

B) weber/m (Wb/m)

C) T/m2

D) Tm2

Answer: D

2) A cube whose edges are 0.10 m long has one corner at the origin of an xyz-coordinate system as shown in Figure 1. A magnetic field with a strength of 0.40 T is applied along the +x-axis. What is the magnetic flux through the shaded face of the cube?

A) 4.0 × 10-1 Tm2

B) 4.0 × 10-2 Tm2

C) 4.0 × 10-3 Tm2

D) 4.0 × 10-4 Tm2

Answer: C

Diff: 2 Page Ref: Sec. 23-2

3) A bar magnet is placed with its north pole pointing toward a coil of wire that has a cross-sectional area of 0.02 m2 and 6 turns, as shown in Figure 2(a). What is the magnitude of the induced emf in the coil of wire?

A) 0.04 V

B) 0.01 V

C) 0.02 V

D) 0 V

Answer: D

4) A bar magnet with its north pole pointing toward a coil of wire with a cross-sectional area of 0.020 m2 and seven turns is thrust into the coil as shown in Figure 2(b). If the rate of change in the strength of the magnetic field caused by the motion of the bar magnet is 0.040 T/s, what is the magnitude of the induced emf in the coil of wire?

A) 5.6 × 10-1 V

B) 5.6 × 10-2 V

C) 5.6 × 10-3 V

D) 5.6 × 10-4 V

Answer: C

5) A conducting rod whose length is 25 cm is placed on a U-shaped metal wire that has a resistance of 8.0 Ω as shown in Figure 3. The wire and the rod are placed in the plane of the paper. A constant magnetic field of strength 0.40 T is applied out of the paper. An applied force moves the rod to the left with a constant speed of 6.0 m/s. What is the magnitude and direction of the induced current in the wire?

A) 75 mA clockwise

B) 75 mA counterclockwise

C) 17 mA counterclockwise

D) 17 mA clockwise

Answer: B

6) A rectangular coil with dimensions of 7.0 cm × 10 cm is dropped from a zero magnetic field position to a 1.2 T magnetic field in 0.10 s. The coil has 60 turns and is perpendicular to the magnetic field. What is induced emf in the coil as a result of this?

A) 6.7 V

B) 8.6 V

C) 5.0 V

D) 2.4 V

Answer: C

7) A rectangular coil with N turns, length L, and width w, as shown in Figure 4, is rotating in a magnetic field B with an angular frequency ω. If the area of the coil is A, what is the induced emf in the coil?

A) ε = NB (Lw) ω sin ωt

B) ε = NBA ω sin ωt

C) ε = NBA (2πf) sin 2πft

D) All of these answers are correct.

Answer: D

8) A rectangular coil lies flat on a horizontal surface. A bar magnet is held above the center of the coil with its south pole pointing down. What is the direction of the induced current in the coil?

A) clockwise

B) counterclockwise

C) There is no current in the coil.

D) None of the other answers is correct.

Answer: C