he motor in a toy car is powered by four batteries in series, which produce a total emf of 7.4 V. The motor draws 2.9 A and develops a 2.1 V back emf at normal speed. Each battery has a 0.16 Ω internal resistance. What is the resistance of the motor in Ω?

Consider the circuit below. The battery has emf 80.0 V, R1=40 ohms, R2= 20 ohms and L= 5.0 mH. Initially the switch is open and no currents are flowing. What is the current through the battery immediately after the switch is closed? a) zero b) 1.3 A c) 2.0 A

15 A defibrillator passes a brief burst of current through the heart to restore normal beating. In one such defibrillator, a 42.7-μF capacitor is charged to 5.90 kV. Paddles are used to make an electric connection to the patient’s chest. A pulse of current lasting 1.00 ms partially discharges the capacitor through the patient. The electrical resistance of the patient (from paddle to paddle) is 240 Ω. How much energy is dissipated in the patient during the 1.00 ms? _____J

A capacitor charging circuit consists of a battery, an uncharged 20 μF capacitor, and a 4.0 kΩ resistor. At t = 0 s, the switch is closed; 0.15 s later, the current is 0.46 mA. What is the battery’s emf?

In (Figure 1), R1R1R_1 = 3.00 ΩΩ, R2R2R_2 = 7.00 ΩΩ, and R3R3R_3 = 4.00 ΩΩ. The battery has negligible internal resistance. The current I2I2 through R2R2 is 3.00 A . What is the emf of the battery? Express your answer with the appropriate units.