Chap 18. Electrical quantities

A resistor of resistance R is connected to a battery of e.m.f. V.

There is a current I in the resistor. Power P is dissipated by the resistor, and in time t the energy transferred is E.

Which expression is correct?

• E = IVt

• E = PIt

• P = VIR

• P = V/R

There is a current of 2.0 A in a resistor for 30s. The potential difference (p.d.) across the resistor is 12V.

How much energy is transferred in the resistor?

• 1.25 J

• 5.0 J

• 180 J

• 720 J

• A

• B

• C

• D

• A

• B

• C

• D

The potential difference across a car headlamp is 12 V. The current in the lamp is 2.5 A.

How much energy is transferred by the lamp in 1.0 hour?

• 1800 J

• 1800 W

• 108 000 J

• 108 000 W

Which produces an electromotive force (e.m.f.)?

• a battery

• a filament lamp

• a resistor

• a spring balance

• A

• B

• C

• D

Which particles move in a metal to cause an electric current?

• electrons

• neutrons

• nucleons

• protons

In an electric circuit, 40 C of electric charge pass a point in 5.0 s.

What is the current in the circuit?

• 0.13 A

• 8.0 A

• 45 A

• 200 A

There is a current of 5.0 A in a resistor.

The potential difference (p.d.) across the resistor is 24 V.

How much energy is transferred in the resistor in 1.0 minute?

• 5.0 J

• 120 J

• 290 J

• 7200 J