Physics 12 Worksheet Physicist: KEY Current Electricity & Circuitry

1. The current through a lightbulb connected across the terminals of a 125-V outlet is 0.50 A. At what rate does the bulb convert electric energy to light? (Assume 100 percent efficiency.)

2. An automobile panel lamp with a resistance of 33 is placed across a 12-V battery. What is the current through the circuit?

3. A 75-W lamp is connected to 125 V. a. What is the current through the lamp?

b. What is the resistance of the lamp?

4. Draw a circuit diagram to include a 60.0-V battery, an ammeter, and a resistance of 12.5- resistor in series. Indicate the ammeter reading and the direction of the current.

5. Draw a series-circuit diagram showing a 4.5-V battery, a resistor, and an ammeter that reads 85 mA. Determine the resistance and label the resistor. Choose a direction for the conventional current and indicate the positive terminal of the battery. Add a voltmeter to measure the potential difference across the resistor.

6. A circuit has 12 of resistance and is connected to a 12-V battery. Determine the change in power if the resistance decreases to 9.0 .

7. For the figure below, the voltmeter reads 70.0 V.

a. Which resistor is the hottest?

50. Since P = I2R and I is constant in a series circuit, the largest value of resistance will produce the most power.

b. What will the ammeter read?

c. Find the total resistance of the circuit.

8. For the figure below, the battery develops 110 V.

a. Which resistor is the coolest?

50.0 . Since P = V2/R and V is constant in a parallel circuit, the largest resistor will dissipate the least power.

b. Find the total resistance of the circuit.

c. What will ammeter 1 read?

d. Show that the current through all parallel branches equals the answer in c).

9. Refer to the figure below to answer the following questions.

a. Determine the total resistance.

b. Determine the current through the 25- resistor.

c. Which resistor is the hottest? Coolest?