Mechanical Aptitude Mechanical Aptitude Basic Electrical Circuits 3 — Questions and Answers
Question 1: An electric motor draws 5 amps from a 240V supply. How much power does it consume?
- 48 watts
- 245 watts
- 1,200 watts (Correct answer)
- 480 watts
Correct answer: 1,200 watts
Power = Voltage × Current = 240V × 5A = 1,200 watts.
Question 2: What happens to the total resistance in a series circuit when an additional resistor is added?
- Total resistance decreases
- Total resistance stays the same
- Total resistance increases (Correct answer)
- Total resistance becomes unpredictable
Correct answer: Total resistance increases
In a series circuit, resistances add together directly, so adding any resistor always increases total resistance.
Question 3: Which of the following is a good conductor of electricity?
- Rubber
- Glass
- Copper (Correct answer)
- Wood
Correct answer: Copper
Copper has very low electrical resistance due to its free electrons, making it an excellent conductor widely used in wiring.
Question 4: In a series circuit with a 12V battery and three identical 4-ohm resistors, what is the voltage across each resistor?
- 12 volts
- 4 volts (Correct answer)
- 1 volt
- 36 volts
Correct answer: 4 volts
Total resistance = 12 ohms, current = 12V/12Ω = 1A; voltage across each resistor = 1A × 4Ω = 4 volts.
Question 5: What is the term for the opposition to the flow of electric current in a conductor?
- Voltage
- Resistance (Correct answer)
- Capacitance
- Inductance
Correct answer: Resistance
Resistance, measured in ohms, is the opposition that a material or component presents to current flow.
Question 6: A circuit has two light bulbs connected in series. When one bulb burns out, what happens to the other?
- The other bulb burns brighter
- The other bulb stays on at normal brightness
- The other bulb also goes out (Correct answer)
- The other bulb flickers
Correct answer: The other bulb also goes out
In a series circuit, a break anywhere opens the entire circuit, stopping current flow through all components.
Question 7: According to Ohm's Law, if voltage across a resistor doubles while resistance stays the same, what happens to current?
- Current is halved
- Current stays the same
- Current doubles (Correct answer)
- Current quadruples
Correct answer: Current doubles
Ohm's Law states I = V/R; if V doubles and R is constant, then I also doubles proportionally.
Mechanical Aptitude Mechanical Aptitude Basic Electrical Circuits 3
An electric motor draws 5 amps from a 240V supply.
How much power does it consume?