Exam 5: Electric Current and Direct-Current Circuits

Use the following figures to answer the next five problems. -An uncharged capacitor and a resistor are connected in series to a battery as shown. If $\varepsilon$ = 15 V, C = 20 $\mu$ F, and R = 4.0 *10⁵ $\Omega$ , the maximum charge on the capacitor is approximately

Use the diagram for the next two problems: -The switch S is initially at position a for a long time. It is then switched to position b. Describe what happens to the light bulb as a function of time when the switch is flipped from a to b?

A resistor of 2 $\Omega$ and another of 3 $\Omega$ are connected in parallel, and this combination is joined in series with a 4- $\Omega$ resistor across a battery. If the current in the 2- $\Omega$ resistor is 2.0 A, the potential drop across the 3- $\Omega$ resistor is

In this circuit, the current in the 4- $\Omega$ resistor is approximately

An uncharged capacitor and a resistor are connected in series to a battery as shown. If $\varepsilon$ = 15 V, C = 20 $\mu$ F, and R = 4.0 * 10⁵ $\Omega$ , the current as a function of time for this circuit is

In this circuit, two batteries, one with a potential difference of 10 V and the other with a potential difference of 20 V, are connected in series across a resistance of 90 $\Omega$ . The power delivered by the 10-V battery is approximately

You want to measure the current through and the voltage difference across a resistor. How should you connect the ammeter and voltmeter to the resistor?

Which of the following statements is true concerning an ideal ammeter and an ideal voltmeter?

In a parallel circuit,

You leave your 120-W light bulb on in your room by mistake while you are at school for 8.5 hours. If the price of electrical energy is $0.085 per kilowatt-hour, how much did it cost you?

Wire A, which is of the same length and material as wire B, has twice the diameter of wire B. If the resistance of wire B is R, what is the resistance of wire A?

When two identical resistors are connected in series across a battery, the total power dissipated by them is 20 W. If these resistors are connected in parallel across the same battery, the total power dissipated is

Each of three identical electric heaters is rated at 1000 W when operated across 100-V lines. When the three are connected in series across a 120-V line, at what rate is electric energy converted to heat energy? (Neglect variation of resistance with temperature.)

A galvanometer has an internal resistance of 200 $\Omega$ and requires a current of 5.0 mA for full-scale deflection. What resistance should be connected in parallel with this galvanometer to make an ammeter that reads 10 A at full-scale deflection?

A 0.12- $\mu$ F capacitor, initially uncharged, is connected in series with a 10-k $\Omega$ resistor and a 12-V battery of negligible internal resistance. Approximately how long does it take the capacitor to reach 90% of its final charge?

The dashed lines represent graphs of the potential as a function of the current for two resistors A and B, respectively. The curve that might reasonably represent a graph of the data taken when the resistors are connected in series is

A wire of length L = 5.0 m and uniform diameter has an electric field of E = 4.0 V/m throughout the wire. The potential difference across the wire is

Doubling the resistance in an RC circuit

The curve that best represents the charge on the capacitor in a charging RC circuit as a function of time is

Use the following figures to answer the next five problems. -An uncharged capacitor and a resistor are connected in series to a battery as shown. If $\varepsilon$ = 15 V, C = 20 $\mu$ F, and R = 4.0 *10⁵ $\Omega$ , the maximum current in the circuit is approximately