Free Circuit Analysis MCQs with Answers
394 Circuit Analysis MCQs from Electrical Engineering, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.
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394 questions · page 18 of 20
- A. 80 m
- B. 60 m
- C. 40 m
- D. 20 m
Explanation: At 1 kW and 200 V, the heater resistance is R = V²/P = 200²/1000 = 40 Ω. With 2 Ω per metre, the required length is 40/2 = 20 m.
Correct answer: 20 m- A. 160 ohms
- B. 80 ohms
- C. 20 ohms
- D. 10 ohms
Explanation: For equal material and length, resistance is inversely proportional to cross-sectional area.
Correct answer: 10 ohms- A. 3/2 Q
- B. 6 Q
- C. 4 Q
- D. 8/3 Q
Explanation: Between two corners of the triangle, one 6 Ω resistor is in parallel with the other two in series, which equal 12 Ω.
Correct answer: 4 Q- A. 9 times
- B. 1/9 times
- C. 1/3 times
- D. 3 times
Explanation: Three identical resistors of R in parallel give R/3, while in series they give 3R.
Correct answer: 1/9 times- A. decrease
- B. increase
- C. remain constant
- D. none of the above
Explanation: Removing part of the heater wire reduces its length and therefore its resistance.
Correct answer: increase- A. 1/9 times
- B. 3 times
- C. 9 times
- D. unchanged
Explanation: With constant volume, making the wire three times longer makes its cross-sectional area one-third as large.
Correct answer: 9 times- A. resistance
- B. inductance
- C. capacitance
- D. impedance
Explanation: An inductive load opposes a sudden change in current and produces a high induced voltage when switched off, which can cause sparking…
Correct answer: inductance- A. magnitude and direction of current remains constant
- B. magnitude and direction of current changes with time
- C. magnitude of current changes with time
- D. magnitude of current remains constant
Explanation: Direct current flows in one direction with a constant magnitude under the ideal definition.
Correct answer: magnitude and direction of current remains constant- A. 100 W lamp will glow brighter
- B. 40 W lamp will glow brighter
- C. Both lamps will glow equally bright
- D. 40 W lamp will fuse
Explanation: At the same rated voltage, lamp resistance is R = V²/P, so the 40 W lamp has greater resistance than the 100 W lamp.
Correct answer: 40 W lamp will glow brighter- A. Reactor
- B. Capacitor
- C. Inductor
- D. Resistor
Explanation: A resistor limits current in both AC and DC circuits because its opposition, R, is present for either type of supply.
Correct answer: Resistor- A. magnetic effect
- B. luminous effect
- C. thermal effect
- D. chemical effect
- E. all above effects
Explanation: Depending on the device, current can produce magnetic, heating, light and chemical effects, such as in motors, heaters, lamps and…
Correct answer: all above effects- A. decrease
- B. increase
- C. remain same
- D. heater will burn out
Explanation: At the same rated voltage, a 100 W bulb has lower resistance than a 40 W bulb because R = V²/P.
Correct answer: increase353. Which of the following quantities remain the same in all parts of a series circuit ____________?
- A. Voltage
- B. Current
- C. Power
- D. Resistance
Explanation: A series circuit has only one path for charge flow, so the same current passes through every component.
Correct answer: Current- A. zero
- B. about 50 ohms
- C. about 500 ohms
- D. infinity
Explanation: An ideal closed switch is a short circuit, so it offers zero resistance and produces no voltage drop.
Correct answer: zero- A. Rl
- B. Ri
- C. either Rl or Ri
- D. none of them
Explanation: In a series circuit the same current flows through both resistances, so the voltage drop V = IR is greater across the larger resistance.
Correct answer: Rl- A. The current through each bulb in same
- B. The voltage across each bulb is not same
- C. The power dissipation in each bulb is not same
- D. None of the above
Explanation: A series circuit has only one path, so the current through every bulb is the same.
Correct answer: The current through each bulb in same- A. there will be heavy current in the main line
- B. rest of the two bulbs will not light
- C. all three bulbs will light
- D. the other two bulbs will light
Explanation: In a parallel circuit, each bulb has an independent branch across the supply.
Correct answer: the other two bulbs will light- A. increases in the branch of the lowest resistance
- B. increases in each branch
- C. is zero in all branches
- D. is zero in the highest resistive branch
Explanation: The main line supplies all parallel branches, so opening it disconnects the source from every branch.
Correct answer: is zero in all branches- A. practically zero
- B. low
- C. high
- D. very high
Explanation: The resistance of a short connecting wire is very small compared with circuit components and is normally neglected in basic circuit…
Correct answer: practically zero- A. 2 watts
- B. 4 watts
- C. 6 watts
- D. 12 watts
Explanation: Power dissipated by a resistor is P = I²R. With I = 2 A and R = 3 ohms, P = 2² × 3 = 12 W.
Correct answer: 12 watts