27. Resistors & DC Circuits

The circuit shown in Fig. E25.30

contains two batteries, each with an emf and an internal resistance, and two resistors. Find (c) the potential difference Vac of point a with respect to point c.

An emf source with ε = 120V, a resistor with R = 80.0Ω, and a capacitor with C = 4.00 μF are connected in series. As the capacitor charges, when the current in the resistor is 0.900 A, what is the magnitude of the charge on each plate of the capacitor?

In the circuit shown in Fig. E26.33 all meters are idealized and the batteries have no appreciable internal resistance.

(a) Find the reading of the voltmeter with the switch S open. Which point is at a higher potential: a or b?

In the circuit shown in Fig. E26.27

find (b) the unknown emfs ε_1 and ε_2.

The batteries shown in the circuit in Fig. E26.24 have negligibly small internal resistances.

Find the current through (a) the 30.0-Ω resistor.

In the circuit shown in Fig. E26.23, ammeter A1 reads 10.0 A and the batteries have no appreciable internal resistance. (a) What is the resistance of R?

The 10.00-V battery in Fig. E26.28 is removed from the circuit and reinserted with the opposite polarity, so that its positive terminal is now next to point a. The rest of the circuit is as shown in the figure. Find (a) the current in each branch.

The 5.00-V battery in Fig. E26.28 is removed from the circuit and replaced by a 15.00-V battery, with its negative terminal next to point b. The rest of the circuit is as shown in the figure. Find (a) the current in each branch.

In the circuit shown in Fig. E26.34, the 6.0-Ω resistor is consuming energy at a rate of 24 J/s when the current through it flows as shown. (b) What are the polarity and emf ε of the unknown battery, assuming it has negligible internal resistance?