Exam 28: Direct Current Circuits

Two identical storage batteries are connected in series, the positive terminal of the first battery to the positive terminal of the second; then they are placed in a circuit. The combination will provide

A 40.0- $\mu$ F capacitor is charged to 120 V and is then connected across a 500- $\Omega$ resistor. The time constant for the circuit is

A 40- $\mu$ F capacitor is charged through a 30-k $\Omega$ resistor. The time needed to charge the capacitor to 70% of its full charge is

A copper bar has dimensions of 2.0 cm $\times$ 3.0 cm $\times$ 5.0 cm. To get the largest resistance for the bar when it is used as a resistor, we should attach the leads to the two opposite sides that have the dimensions

An ideal voltmeter has

A 10-A current flows through the 3.0- $\Omega$ resistor that is part of a parallel combination of 2.0- $\Omega$ , 3.0- $\Omega$ , and 4.0- $\Omega$ resistors. The current flowing through the 2.0- $\Omega$ resistor is

The current through the 15.0- $\Omega$ resistor in the figure here is

A copper wire is stretched to become 10% longer. Its resistance

In the figure here, the equivalent resistance between points A and B_, when a wire is connected between points C and D, is

A 40.0- $\mu$ F capacitor is charged to 120 V and is then connected across a 500- $\Omega$ resistor. Just after the capacitor is connected to the resistor, the current through the resistor is

A series combination of an uncharged capacitor and a resistor is connected to a battery. Just after the combination is connected to the battery,

A 3.0-k $\Omega$ resistor is connected in series with a 2.0- $\mu$ F initially uncharged capacitor. The RC combination is charged by a 6.0-V battery. The change in voltage between t = RC and t = 3RC is

In the circuits shown here all the batteries have the same emf, and all the bulbs are identical. The circuit with the greatest current is

A difference in potential is applied across the combination of a 40-W lightbulb and a 60-W lightbulb connected in series. The 40-W bulb

The current through the 10.0- $\Omega$ resistor in the figure here is

Two identical heating coils are connected to a constant-voltage line. To get the largest amount of heat per minute, the coils should be connected

In the figure here, the difference in potential V_A - V_B is

The curve that best represents the current in a discharging RC circuit is

In the figure here, the difference in potential V_C - V_D is

The typical drift speed of electrons in a metal at room temperature is