Energy and Power in Electric Circuits

What is power in electrical circuits?

• The rate at which energy is transferred

• The total amount of energy in a circuit

• The resistance in a circuit

• The voltage across a circuit

Using the equation P = \frac{E}{t}, if energy is 1200 joules and time is 30 seconds, what is the power?

• 40 watts

• 36 watts

• 45 watts

• 50 watts

In the equation P = VI, what does V represent?

• Volume

• Velocity

• Voltage

• Viscosity

Calculate the current in a circuit where power is 480 watts and voltage is 240 volts using P = VI.

• 2 amperes

• 720 amperes

• 1.5 amperes

• 3 amperes

Using P = I^2R, what is the power if current is 3 amperes and resistance is 4 ohms?

• 24 watts

• 36 watts

• 12 watts

• 48 watts

Why are high voltages used in power transmission lines?

• To increase energy loss

• To decrease the size of cables

• To reduce current and energy losses

• To increase current flow

Using P = \frac{V^2}{R}, calculate the power when voltage is 12 volts and resistance is 6 ohms.

• 24 watts

• 72 watts

• 18 watts

• 36 watts

What happens to a fuse when the current exceeds its maximum tolerance?

• It becomes more conductive

• It melts

• It increases resistance

• It cools down

For a 100W light bulb connected to 240V mains, what is the approximate current?

• 0.42 amperes

• 0.52 amperes

• 0.62 amperes

• 0.72 amperes

Calculate the energy transferred when power is 60 watts for 120 seconds using E = Pt.

• 7200 joules

• 6000 joules

• 5400 joules

• 4800 joules