1. (Knight Problem 30.11) The metal equilateral triangle in FIGURE EX30.11, 20 cm on each side, is halfway into a 0.10 T magnetic field. a. What is the magnetic flux through the triangle? [Answer: 8.7 10-4 Wb.] b. If the magnetic field strength decreases, what is the direc- tion of the induced current in the triangle? [Answer: Clock- wise.] 0.10 TXX X X X X X X X 20 cm x xx x xxx x X X X X! XXX XI FIGURE EX30.11 2. (Knight Problem 30.13) The loop in FIGURE EX30.13 is being pushed into the 0.20 T magnetic field at 50 m/s. The resistance of the loop is 0.10 2. What are the direction and the magnitude of the current in the loop? [Answer: 5.0 A, clockwise.] B=0.20 T 50 m/s 5.0 cm FIGURE EX30.13 3. (Knight Problem 30.19) The magnetic field in FIGURE EX30.19 is decreasing at the rate 0.10 T/s. What is the acceleration (magnitude and direction) of a proton initially at rest at points a to d? [Answer: a. 1.6 x 10 m/s, up. b. 0 m/s. c. 4.8 x 10 m/s, down. d. 9.6 104 m/s, down.] 2.0 cm 1 cm 1 cm 1 cm FIGURE EX30.19 4. (Knight Problem 30.25) What is the potential difference across a 10 mH inductor if the current through the inductor drops from 150 mA to 50 mA in 10 ms? What is the direc- tion of this potential difference? That is, does the potential increase or decrease along the direction of the current? [An- swer: 100 V, increases.] 5. (Knight Problem 30.29) An FM radio station broadcasts at a frequency of 100 MHz. What inductance should be paired with a 10 pF capacitor to build a receiver circuit for this station? [Answer: 0.25 H.] Question 1 S N The figure provided, a loop of copper wire is moved between two permanent magnets. What force, if any, will the copper wire experience? O The copper wire will experience a repulsive magnetic force. The copper wire will experience an attractive magnetic force. The copper wire will not experience any magnetic force. Question 2 XXX R In the figure provided, a magnetic field is constant. What is the direction of the current in the loop of wire? 000 Counterclockwise There is no current in the loop of the wire. Clockwise Question 3 A B A magnet is pushed towards a conducting look of wire as shown above, inducing a counter-clockwise current in the loop. What is the magnetic pole of the magnet at end B? O North pole. None. South pole. Question 4 -0000 L A 7.50 uF capacitor is connected to a 12.5 mH inductor as shown in the circuit above. What happens to the current when the switch is closed? The current will begin to oscillate in the circuit. No currrent flows in the circuit. The current flows and is disspated in the inductor.