Mechanical Aptitude Mechanical Aptitude Basic Electrical Circuits 2 — Questions and Answers
Question 1: In a parallel circuit with three branches, if one branch is opened (disconnected), what happens to current in the other two branches?
- Current in the other branches increases
- Current in the other branches stays the same (Correct answer)
- Current in the other branches drops to zero
- Current in the other branches decreases by one-third
Correct answer: Current in the other branches stays the same
In a parallel circuit, each branch operates independently at the same voltage, so opening one branch does not affect current in the remaining branches.
Question 2: A resistor is color-coded with bands: yellow, violet, red, gold. What is its resistance value?
- 470 ohms ±5%
- 4,700 ohms ±5% (Correct answer)
- 47 ohms ±5%
- 47,000 ohms ±5%
Correct answer: 4,700 ohms ±5%
Yellow=4, violet=7, red=×100 multiplier gives 4,700 ohms, and gold indicates ±5% tolerance.
Question 3: Which device is used to measure electrical current in a circuit?
- Voltmeter
- Ohmmeter
- Ammeter (Correct answer)
- Wattmeter
Correct answer: Ammeter
An ammeter measures current flow (in amperes) and must be connected in series with the circuit.
Question 4: What is the total resistance when a 10-ohm and a 40-ohm resistor are connected in parallel?
- 50 ohms
- 25 ohms
- 8 ohms (Correct answer)
- 4 ohms
Correct answer: 8 ohms
Using 1/R_total = 1/10 + 1/40 = 4/40 + 1/40 = 5/40, so R_total = 40/5 = 8 ohms.
Question 5: A 120V circuit has a 20A circuit breaker. What is the maximum power load this circuit can handle?
- 6 watts
- 140 watts
- 2,400 watts (Correct answer)
- 600 watts
Correct answer: 2,400 watts
Power = Voltage × Current = 120V × 20A = 2,400 watts maximum.
Question 6: What is the primary purpose of a fuse in an electrical circuit?
- To increase voltage to appliances
- To protect the circuit from excessive current (Correct answer)
- To store electrical energy for later use
- To convert AC to DC power
Correct answer: To protect the circuit from excessive current
A fuse contains a metal element that melts and breaks the circuit when current exceeds a safe level, protecting wiring and components.
Question 7: In which type of circuit does electricity have only one path to flow from the source back to the source?
- Parallel circuit
- Series circuit (Correct answer)
- Bridge circuit
- Compound circuit
Correct answer: Series circuit
In a series circuit, all components are connected end-to-end forming a single continuous path for current.
Mechanical Aptitude Mechanical Aptitude Basic Electrical Circuits 2
In a parallel circuit with three branches, if one branch is opened (disconnected), what happens to current in the other two branches?