Electronics MCQ Quiz – Part 1
1. In the power formula P = I × V, what does the letter I represent?
Correct Answer: C) Current
I stands for electric current measured in amperes. Power equals current times voltage.
2. Hertz is the unit of which quantity?
Correct Answer: B) Cycles per second
One hertz means one cycle per second. Hertz measures frequency.
3. Which quantity is measured in amperes?
Correct Answer: C) Electric current
Amperes measure how much electric charge flows per second, which is current.
4. Which of the following is a unit of electrical power?
Correct Answer: C) Watts
Watts measure power, or how quickly energy is used or produced.
5. Three amps equals how many milliamps?
Correct Answer: D) 3,000
1 ampere equals 1,000 milliamperes, so 3 A = 3,000 mA.
6. Which of the following is the SI unit representing one cycle per second?
Correct Answer: D) Hertz
Hertz is the SI unit for frequency and means cycles per second.
7. Ohm’s law states V = I × R. If a circuit draws 20 A with a resistance of 12 Ω, what is the voltage?
Correct Answer: C) 240 V
Voltage equals current times resistance, so 20 A × 12 Ω = 240 V.
8. If amperes equal volts divided by ohms, then volts equal what?
Correct Answer: D) Amperes × ohms
Rearranging I = V ÷ R gives V = I × R, so volts equal current times resistance.
9. A circuit has a voltage of 24 V and a resistance of 6 ohms. What is the current in the circuit?
Correct Answer: A) 4 A
Current is voltage divided by resistance: 24 ÷ 6 = 4 A.
10. If a circuit has 10 amps of current and 6 ohms of resistance, what is the voltage?
Correct Answer: C) 60
Voltage = current × resistance, so 10 A × 6 Ω = 60 V.
11. If a circuit with a 120-volt supply is protected by a 5-amp breaker, what is the largest number of watts an appliance on this circuit can safely use?
Correct Answer: C) 600 W
Power = voltage × current. 120 V × 5 A = 600 W maximum before the breaker trips.
12. Ohm’s law calculation: If voltage is 8 V and resistance is 4 Ω, what is the current?
Correct Answer: B) 2 amps
I = V ÷ R = 8 ÷ 4 = 2 A.
13. In a series circuit, what is the relationship between the currents flowing through each resistor?
Correct Answer: B) The current is the same through each resistor
A series circuit has a single path, so the same current flows through every component.
14. In a parallel circuit, if one of the light bulbs burns out, what will happen to the others?
Correct Answer: C) The other bulbs will stay lit
In parallel, each bulb has its own path. One failing does not affect the others.
15. What type of circuit has both series and parallel loads?
Correct Answer: D) Series-parallel circuit
A series-parallel circuit contains some parts in series and others in parallel.
16. A circuit with zero resistance is best described as which condition?
Correct Answer: B) Short circuit
Zero or near-zero resistance lets current surge, which is a short circuit and can be dangerous.
17. What happens to current flow when resistance in a circuit increases, assuming voltage stays the same?
Correct Answer: B) Current decreases
According to Ohm’s law, I = V ÷ R, so higher resistance reduces current for the same voltage.
18. Which component stores energy in an electric field?
Correct Answer: B) Capacitor
Capacitors store electric charge between two plates, creating an electric field.
19. What is the main function of a diode in a circuit?
Correct Answer: B) Control current direction
Diodes allow current to flow in one direction and block it the other way.
20. A device that converts electrical energy into mechanical energy is a:
Correct Answer: C) Motor
A motor uses electricity to produce motion through magnetic interaction.
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