CHAPTER 26 HOMEWORK
1. (p.679. Ex.4) What is the internal resistance of a 12.0V car battery whose terminal voltage drops to 9.8V when the starter draws 60A? What is the resistance of the starter?
2. (p.679 Ex.10) Three 1.20kW resistors can be connected together in four different ways, making combinations of series and/or parallel circuits. What are these four ways and what is the net resistance in each case?
3. (p.680 Ex.19) Consider the network of resistors show in Fig.26-36. Answer qualitatively: (a) What happens to the voltage across each resistor when the switch S is closed? (b) what happens to the current through each when the switch is closed? (c) What happens to the power output of the batter when the switch is closed? (d) Let R1 = R2 = R3 = R4 = 100W and V = 45.0V. Determine the current through each resistor before and after closing the switch. Are your qualitative predictions confirmed?
4. (p.680 Ex.25) Determine the magnitudes and directions of the currents through R1 and R2 in Fig. 26-39.
5. (p.681 Ex.33) Suppose the 6.0-V battery in Fig. 26-43 is replaced by a unknown emf e. If the current through the 10-W resistor is I2 = 0.30A to the left, what is e? Assume r = 1.0W.
6. (p.681 Ex.42) The RC circuit of Fig. 26-19a has R = 6.7kW and C = 6.0mF. The capacitor is at voltage Vo at t = 0 , when the switch is closed. How long does it take the capacitor to discharge to 1.0 percent of its initial voltage?
7*. (p.680 Ex.22) A 3.8-kW and a 2.1-kW resistor are connected in parallel: This combination is connected in series with a 1.8-kW resistor If each resistor is rated at 1/2W, what is the maximum voltage that can be applied across the whole network?8*. (p.681 Ex.36) Determine the net resistance of the network shown in Fig. 26-44 (a) between points a and C, and (b) between points a and b. Assume R' = R. [Hint: Use symmetry.]
9*. (p.682 Ex.45) (a)Determine the time constant for charging the capacitor in the circuit of Fig. 26-47. [Hint: Use Kirchhoff's rules] (b)What is the maximum charge on the capacitor?
