9.1. The figure below and to the right shows an increasing magnetic field and the electric field that accompanies it according to Faraday's law. If the magnetic field is increasing at an increasing rate.... (a) Is the electric field magnitude constant, increasing, or decreasing? (b) Does the behavior of the electric field produce an additional magnetic field? If so, what is the direction of the additional magnetic field? Does it reinforce or coun- teract the original magnetic field? É into page × X B É out of page 9.2. A parallel plate capacitor has a steady charging current of 5.0 A. (Assume the area of the plates is much greater than their separation distance.) (a) What is the time rate of change of the electric flux between the plates of the capacitor? (b) What is the displacement current between the plates? (c) How do your answers to (a) and (b) change if there is a dielectric for which <= 1.5 between the plates? 9.3. A heart pacemaker fires 72 times a minute, each time a 25 nF capacitor is charged (by a battery in series with a resistor) to 0.632 of its full voltage. What is the value of the resistance? 9.4. A heart defibrillator being used on a patient has an RC time constant of 10 ms due to the resistance of the patient and the capacitance of the defibrillator. (a) If the total capacitance of the system is 8.0 μF, what is the total resistance of the system? (Almost all of this is the resistance of the path through the patient's body.) (b) If the initial voltage is 12 kV, how long does it take to decline to 600 V? 9.5. A coil with inductance L = 3.0 H and a resistance R = 100 2 carries a steady current of 2.0 A. (a) What is the energy stored in the magnetic field of the coil? (b) What is the energy per second dissipated in the resistance of the coil? 9.6. A circuit with an inductor (20 mH) and a resistor (5.02) is powered by a 12V power source. (a) What is the time constant of the circuit TL? (b) What is the initial current through the resistor when the power source is turned on? (c) What is the final current through the resistor? (d) What is the current through the resistor at time t = 2TL? (e) What is the emf induced across the inductor at time t = = 2TL? 19 9.7. A step-up transformer is designed so that the output of its secondary winding is 2000 V (rms) when the primary winding is connected to a 110 V (rms) line voltage. (a) If there are 100 turns in the primary winding, how many turns are there in the secondary winding? (b) If a resistor connected across the secondary winding draws an rms current of 0.75 A, what is the current in the primary winding? 9.8. A transformer is used to supply a 12 V model train with power from a 110 V wall plug. The train operates at 50 W of power. (a) What is the rms current in the secondary coil of the transformer? (b) What is the rms current in the primary coil? (c) What is the ratio of the number of primary to secondary turns? (d) What is the resistance of the train? (e) What is the resistance seen by the 110V source?