b) Calculate each of the unknown currents I1, I2, and I3 for the circuit. (Give the magnitude of the current only.) I1 = ______ A I2 = ______ A I3 =  ______A

You have a faculty position at a community college and are m (caching a class in automotive technology. You are deep in a discussion of using jumper cables to start a car with a dead battery from a car with a fresh battery. You have drawn the circuit diagram in Figure P27.16 to explain the process. The battery on the left is the live batten- in the correctly functioning car, with emf and internal resistance RL where the L. subscript refers to live. Its terminals are connected directly across those of the dead battery, in the middle of the diagram, with emf and internal resistance RD where the D subscript refers to "dead Then, the starter in the car with the dead battery is activated by closing the ignition switch, allowing the car to start. The resistance of the starter is Rs. A student raises his hand and asks, So is the dead battery being charged while the starter is operating? How do you respond?

A battery has some internal resistance. (i) Clan the potential difference across the terminals of the battery be equal to its emir (a) no (b) yes, if the battery is absorbing energy by electrical transmission (c) yes, if more than one wire is connected to each let initial (e) yes, if the current in the battery is zero (e) yes, with no special condition required. (ii) Can the terminal voltage exceed the emf? Choose your answer from the same possibilities as in part (i).

A person with body resistance between his hands of 1.00 k accidentally grasps the terminals of a 20.0-kV power supply. (Do NOT do this!) (a) Draw a circuit diagram to represent the situation. (b) If the internal resistance of the power supply is 2000 , what is the current through his body? (c) What is the power dissipated in his body? (d) If the power supply is to be made safe by increasing its internal resistance, what should the internal resistance be for the maximum current in this situation to be 1.00 mA or less? (e) Will this modification compromise the effectiveness of the power supply for driving low-re si stance devices? Explain your reasoning,

Unreasonable Results (a) Calculate the capacitance needed to get an RC time constant of 1,00x103 s with a 0.100- resistor, (b) What is unreasonable about this result? (c) Which assumptions are responsible?

Three 100- resistors are connected as shown in Figure P21.41 The maximum power that can safely be delivered to any one resistor is 25.0 W. (a) What is the maximum potential difference that can be applied to the terminals a and b? (b) For the voltage determined in part (a), what is the power delivered to each resistor? (c) What is the total power delivered to the combination of resistors?

Unreasonable Results A 1.58-V alkaline cell with a 0.200- internal resistance is supplying 8.50 A to a load, {a) What is its terminal voltage? (b) What is the value of the load resistance? (c) What is unreasonable about these results? (d) Which assumptions are unreasonable or inconsistent?

Integrated Concepts (a) What is the average power output of a heart defibrillator that dissipates 400 J of energy in 10.0 ms? (b) Considering the high-power output, why doesn’t the defibrillator produce serious burns?

Referring to Figure CQ28.6, describe what happens to the lightbulb after the switch is closed. Assume the capacitor has a large capacitance and is initially uncharged. Also assume the light illuminates when connected directly across the battery terminals.

Construe! Your Own Problem Consider a rechargeable lithium cell that is to be used to power a camcorder. Construct a problem in which you calculate the internal resistance of the cell during normal operation. Also, calculate the minimum voltage output of a battery charger to be used to recharge your lithium cell. Among the things to be considered are the emf and useful terminal voltage of a lithium cell and the current it should be able to supply to a camcorder.