Practice Quiz 6

1) 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 face of the cube along the yz plane at x = 0? A) 4.0 × 10-2 Tm2 B) -4.0 × 10-3 Tm2 C) -4.0 × 10-2 Tm2 D) 4.0 × 10-3 Tm2 Answer: B

2) A rectangular loop of wire carrying a current of 2.0 A that can rotate is placed in a magnetic field with a strength of 0.40 T as shown in Figure -2. The length of the loop L is 0.16 m and its width w is 0.040 m. What is the magnetic flux through the loop when the plane of the loop is perpendicular to the magnetic field? A) 13 × 10-3 Tm2 B) -2.6 × 10-3 Tm2 C) 0.80 Tm2 D) 2.6 × 10-3 Tm2 Answer: D

3) A bar magnet with its south pole pointing toward a coil of wire of cross-sectional area 0.020 m2 and seven turns is thrust into the coil as shown in Figure 3(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 that coil of wire? A) 5.6 × 10-3 V B) 5.6 × 10-2 V C) 5.6 × 10-1 V D) 5.6 × 10-4 V Answer: A

4) A bar magnet with its south pole pointing toward a loop of wire of cross-sectional area 0.020 m2 and total number of turns equal to six is stationary near the loop of wire shown in Figure 3(a). What is the direction of the induced emf in that loop of wire (when looking at the end of the coil where the S pole is coming toward you)? A) clockwise B) counterclockwise C) There is no emf induced. D) None of the other answers is correct. Answer: C

5) A conducting rod whose length is 25 cm is placed on a U-shaped metal wire that has a resistance R of 8 Ω as shown in Figure 23-5. The wire and the rod are in the plane of the paper. A constant magnetic field of strength 0.4 T is applied perpendicular and into the paper. An applied force moves the rod to the right with a constant speed of 6 m/s. What is the magnitude of the induced emf in the wire? A) 0.2 V B) 0.4 V C) 0.5 V D) 0.6 V Answer: D

6) A conducting rod with a length of 25 cm is placed on a U-shaped metal wire that has a resistance R of 8.0 Ω as shown in Figure 23-5. The wire and the rod are placed in the plane of the paper. A constant magnetic field of strength 0.40 T is applied perpendicular into the paper. An applied force moves the rod to the right with a constant speed of 6.0 m/s. What is the magnitude and direction of the induced current in the wire? A) 17 mA clockwise B) 17 mA counterclockwise C) 75 mA counterclockwise D) 75 mA clockwise Answer: C

7) A constant magnetic field is applied perpendicular to the plane of a square, single-turn coil with each side equal to 15 cm. If the area of the coil decreases at a rate of 0.20 m2/s, an emf of 20 mV is induced in that coil. What is the strength of the magnetic field applied to the coil? A) 0.10 T B) 0.20 T C) 0.30 T D) 0.40 T Answer: A

8) A rectangular coil of N turns, length L = 25 cm, and width w = 15 cm, as shown in Figure 23-9, is rotating in a magnetic field of 1.6 T with a frequency of 75 Hz. If the coil develops a sinusoidal emf of maximum value 56.9 V, what is the value of N? A) 2 B) 4 C) 6 D) 8 Answer: A

9) A circular coil with 600 turns has a radius of 15 cm. The coil is rotating about an axis perpendicular to a magnetic field of 0.020 T. If the maximum induced emf in the coil is 1.6 V, at what angular frequency is the coil rotating? A) 0.30 rad/s B) 0.60 rad/s C) 1.9 cycles/sec D) 1.9 rad/s Answer: D

10) 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. If the magnet is dropped from this position, 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: A