Resistors and Circuits

The equivalent (total) resistance of a parallel circuit is always

• greater than the smallest resistance

• less than the smallest resistance

• greater than the greatest resistance

• the sum of the individual resistances

What is the resistance of a lamp operating at 120 volts and using 0.5 amps of current?

• 240 Ω

• 60 Ω

• 0.5 Ω

• 120.5 Ω

How much power is dissipated in a bulb with a voltage of 10 V and a current of 4 A?

• 14 W

• 40 W

• 2.5 W

• 0.4 W

A motor has a resistance of 100 Ω. It is designed to operate on 120 V. What is the power consumed by the motor?

• 1.2 W

• 12,000 W

• 144 W

• 0.83 W

Two resistors, 120 ohms and 240 ohms, are placed in series. Which one of the following values is closest to their total effective resistance in Ohms ?

• 360

• 120

• 80

• 0.5

Two resistors, 120 ohms and 150 ohms, are connected together in parallel. Which one of the following values is closest to their total effective resistance in Ohms?

• 270

• 135

• 67

• 1.3

Three resistors are connected together, with two 180 ohm in parallel and a 270 ohm in series with them, as shown below. Which of the following values is closest to their total effective resistance in Ohms?

• 630

• 360

• 154

• 30

• 33mA

• 78mA

• 400mA

• None of the above – no current would flow.

What is the potential difference across the 60 ohm resistor in series with a 150 ohm resistor in the following circuit?

• 2.5V

• 4.0V

• 6.5V

• 10V

What is the potential difference across the output when the light illumination is 1000 lux?

• 3.0V

• 4.5V

• 6.0V

• 7.5V