What is the formula for electric power in terms of voltage and current?
A
P = V × I B
P = V / I C
P = I / V D
P = V + I
Analysis & Theory
Electric power (P) is the product of voltage (V) and current (I): P = V × I.
What is the unit of electrical energy?
A
Watt B
Joule C
Coulomb D
Volt
Analysis & Theory
The SI unit of energy is the Joule (J).
How many joules are in 1 kilowatt-hour (kWh)?
A
1000 J B
3600 J C
360,000 J D
3,600,000 J
Analysis & Theory
1 kWh = 1000 W × 3600 s = 3,600,000 Joules.
If a device draws 2A current at 12V, how much power does it consume?
A
6W B
14W C
24W D
10W
Analysis & Theory
P = V × I = 12V × 2A = 24W.
Which formula is used to calculate power using resistance and current?
A
P = I × R B
P = I² × R C
P = R / I D
P = I / R
Analysis & Theory
Using Ohm's Law: P = I² × R.
What is the unit of electric power?
A
Watt B
Joule C
Ampere D
Ohm
Analysis & Theory
The SI unit of power is the Watt (W).
A 100W bulb glows for 5 hours. What is the energy consumed?
A
50 Wh B
500 Wh C
5000 Wh D
5 kWh
Analysis & Theory
Energy = Power × Time = 100W × 5h = 500 Wh.
Which of the following is true about power in resistive AC circuits?
A
Power = Voltage × Current × sin(θ) B
Power = Voltage × Current × cos(θ) C
Power = Voltage × Current D
Power = Voltage / Current
Analysis & Theory
In purely resistive AC circuits, voltage and current are in phase, so power = V × I.
What is the energy used if a 60W fan runs for 10 hours?
A
600 Wh B
6 kWh C
60 kWh D
6000 Wh
Analysis & Theory
Energy = 60W × 10h = 600 Wh = 0.6 kWh.
If a resistor dissipates 40W of power at 10V, what is the current?
A
2A B
4A C
6A D
0.25A
Analysis & Theory
P = V × I → I = P / V = 40 / 10 = 4A.