### Short Answer

## 19.1 Ohm's law

True or false—it is possible to produce nonzero DC current by adding together AC currents.

- false
- true

What type of current is used in cars?

- alternating current
- indirect current
- direct current
- straight current

What is the current through a 100-Ω resistor with 12 V across it?

- 0
- 0.12 A
- 8.33 A
- 1,200 A

## 19.2 Series Circuits

Given a circuit with one 9-V battery and with its negative terminal connected to ground. The two paths are connected to ground from the positive terminal: the right path with a 20-Ω and a 100-Ω resistor and the left path with a 50-Ω resistor. How much current will flow in the right branch?

- $$\frac{\text{9}}{\text{120}}$$
- $$\frac{\text{9}}{\text{100}}$$
- $$\frac{\text{9}}{\text{50}}$$
- $$\frac{\text{9}}{\text{20}}$$

## 19.3 Parallel Circuits

Ten 100-Ω resistors are connected in series. How can you increase the total resistance of the circuit by about 40 percent?

- Adding two 10-Ω resistors increases the total resistance of the circuit by about 40 percent.
- Removing two 10-Ω resistors increases the total resistance of the circuit by about 40 percent.
- Adding four 10-Ω resistors increases the total resistance of the circuit by about 40 percent.
- Removing four 10-Ω resistors increases the total resistance of the circuit by about 40 percent.

In the circuit shown, through which resistor(s) does the most current flow? Through which does the least flow? Explain.

- The most current flows through the 15-Ω resistor because all the current must pass through this resistor.
- The most current flows through the 20-Ω resistor because all the current must pass through this resistor.
- The most current flows through the 25-Ω resistor because it is the highest resistance.
- The same current flows through the all the resistor because all the current must pass through each of the resistors.

## 19.4 Electric Power

You want to increase the power dissipated in a circuit. You have the choice between doubling the current or doubling the resistance, with the voltage remaining constant. Which one would you choose?

- doubling the resistance
- doubling the current

You want to increase the power dissipated in a circuit. You have the choice between reducing the voltage or reducing the resistance, with the current remaining constant. Which one would you choose?

- reduce the voltage to increase the power
- reduce the resistance to increase the power

What power is dissipated in the circuit consisting of 310-Ω resistors connected in series across a 9.0-V battery?

- The power dissipated is 2430 W.
- The power dissipated is 270 W.
- The power dissipated is 2.7 W.
- The power dissipated is 0.37 W.

What power is dissipated in a circuit consisting of three 10-Ω resistors connected in parallel across a 9.0-V battery?

- The power dissipated is 270 W.
- The power dissipated is 30 W.
- The power dissipated is 24 W.
- The power dissipated is 1/24 W.