Rectifiers & Filters — MH-CET Physics MCQs with Solutions
Free MH-CET Physics Rectifiers & Filters MCQs with step-by-step solutions (21 questions). Part of Semiconductor Devices. Practise online on Prepizo — no login needed.
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Questions with solutions
Q1 — Rectifiers & Filters · easy · theory
A rectifier is a circuit that converts:
A. Low voltage into high voltage
B. Direct current into alternating current
C. Current into voltage
D. Alternating current into direct current ✓ Correct
Solution: It exploits the one-way conduction of a junction diode.
Q2 — Rectifiers & Filters · easy · theory
A half-wave rectifier uses:
A. Two diodes
B. One diode ✓ Correct
C. No diode at all
D. Four diodes
Solution: It passes only one half of each input cycle and blocks the other.
Q3 — Rectifiers & Filters · medium · theory
A full-wave centre-tap rectifier and a bridge rectifier use respectively:
A. One and two diodes
B. Four and two diodes
C. Two and four diodes ✓ Correct
D. Two and two diodes
Solution: The bridge arrangement avoids the need for a centre-tapped transformer at the cost of two extra diodes.
Q4 — Rectifiers & Filters · medium · theory
In a half-wave rectifier supplied at $50\text{ Hz}$, the fundamental ripple frequency of the output is:
A. $50\text{ Hz}$ ✓ Correct
B. $25\text{ Hz}$
C. Zero
D. $100\text{ Hz}$
Solution: Only one pulse is delivered per input cycle, so the ripple repeats at the supply frequency.
Q5 — Rectifiers & Filters · medium · theory
In a full-wave rectifier supplied at $50\text{ Hz}$, the fundamental ripple frequency is:
A. $25\text{ Hz}$
B. $50\text{ Hz}$
C. $100\text{ Hz}$ ✓ Correct
D. $200\text{ Hz}$
Solution: Both halves of the input cycle produce an output pulse, doubling the ripple frequency.
Q6 — Rectifiers & Filters · medium · theory
A capacitor filter connected across the load of a rectifier:
A. Converts the DC back into AC
B. Reduces the DC output to zero
C. Smooths the output by charging at the peaks and discharging between them ✓ Correct
D. Increases the ripple in the output
Solution: A large capacitance holds the voltage up during the gaps between pulses.
Q7 — Rectifiers & Filters · medium · theory
A full-wave rectifier is preferred to a half-wave rectifier because it has:
A. A lower output voltage
B. No need for any diodes
C. Higher efficiency and lower ripple ✓ Correct
D. Lower efficiency but simpler construction
Solution: It uses both halves of the input, roughly doubling the DC output for the same input.
Q8 — Rectifiers & Filters · hard · theory
A bridge rectifier has the practical advantage that it:
A. Produces an alternating output
B. Uses only one diode
C. Has a ripple frequency equal to the supply frequency
D. Does not require a centre-tapped transformer ✓ Correct
Solution: This makes the transformer simpler and the peak inverse voltage on each diode lower.
Q9 — Rectifiers & Filters · easy · numerical
A half-wave rectifier is supplied from a $50\text{ Hz}$ mains. The ripple frequency in the output is:
A. Zero
B. $100\text{ Hz}$
C. $25\text{ Hz}$
D. $50\text{ Hz}$ ✓ Correct
Solution: One output pulse per input cycle gives a ripple at the supply frequency.
Q10 — Rectifiers & Filters · easy · numerical
A full-wave rectifier is supplied from a $50\text{ Hz}$ mains. The ripple frequency in the output is:
A. $50\text{ Hz}$
B. $25\text{ Hz}$
C. $150\text{ Hz}$
D. $100\text{ Hz}$ ✓ Correct
Solution: Two pulses per input cycle double the ripple frequency.
Q11 — Rectifiers & Filters · easy · numerical
A half-wave rectifier is supplied at $60\text{ Hz}$. The ripple frequency is:
A. $60\text{ Hz}$ ✓ Correct
B. $120\text{ Hz}$
C. Zero
D. $30\text{ Hz}$
Solution: The ripple frequency of a half-wave rectifier equals the supply frequency.
Q12 — Rectifiers & Filters · easy · numerical
A full-wave rectifier is supplied at $60\text{ Hz}$. The ripple frequency is:
A. $180\text{ Hz}$
B. $60\text{ Hz}$
C. $120\text{ Hz}$ ✓ Correct
D. $30\text{ Hz}$
Solution: A full-wave circuit doubles the supply frequency in its output ripple.
Q13 — Rectifiers & Filters · hard · numerical
For a half-wave rectifier with peak current $I_m$, the average (DC) output current is:
A. $\dfrac{I_m}{\pi}$ ✓ Correct
B. $\dfrac{2I_m}{\pi}$
C. $\dfrac{I_m}{2}$
D. $\dfrac{I_m}{\sqrt{2}}$
Solution: Averaging a half sine over the full period gives $\dfrac{I_m}{\pi} \approx 0.318I_m$.
Q14 — Rectifiers & Filters · hard · numerical
For a full-wave rectifier with peak current $I_m$, the average (DC) output current is:
A. $I_m$
B. $\dfrac{I_m}{2}$
C. $\dfrac{2I_m}{\pi}$ ✓ Correct
D. $\dfrac{I_m}{\pi}$
Solution: Both half cycles contribute, giving $\dfrac{2I_m}{\pi} \approx 0.637I_m$.
Q15 — Rectifiers & Filters · hard · numerical
The RMS value of the output current of a half-wave rectifier of peak current $I_m$ is:
A. $\dfrac{I_m}{2}$ ✓ Correct
B. $I_m$
C. $\dfrac{I_m}{\sqrt{2}}$
D. $\dfrac{I_m}{\pi}$
Solution: Because the current is zero for half of each cycle, the RMS value is $\dfrac{I_m}{2}$.
Q16 — Rectifiers & Filters · hard · numerical
The maximum theoretical efficiency of a half-wave rectifier is approximately:
A. $40.6\%$ ✓ Correct
B. $50\%$
C. $100\%$
D. $81.2\%$
Solution: Half the input waveform is discarded, which limits the achievable conversion efficiency.
Q17 — Rectifiers & Filters · hard · numerical
The maximum theoretical efficiency of a full-wave rectifier is approximately:
A. $40.6\%$
B. $50\%$
C. $81.2\%$ ✓ Correct
D. $100\%$
Solution: Using both halves of the input doubles the efficiency of the half-wave circuit.
Q18 — Rectifiers & Filters · hard · numerical
The ripple factor of a half-wave rectifier is approximately:
A. $2.0$
B. $0.48$
C. $0.5$
D. $1.21$ ✓ Correct
Solution: A value greater than unity means the AC component exceeds the DC component, so filtering is essential.
Q19 — Rectifiers & Filters · hard · numerical
The ripple factor of a full-wave rectifier is approximately:
A. $0.48$ ✓ Correct
B. $1.21$
C. $1.0$
D. $0.8$
Solution: The smoother output of a full-wave circuit needs much less filtering.
Q20 — Rectifiers & Filters · hard · numerical
A half-wave rectifier has a peak output current of $10\text{ mA}$. Its DC output current is approximately:
A. $6.37\text{ mA}$
B. $5\text{ mA}$
C. $7.07\text{ mA}$
D. $3.18\text{ mA}$ ✓ Correct
Solution: $I_{dc} = \dfrac{I_m}{\pi} = \dfrac{10}{3.1416} \approx 3.18\text{ mA}$.
Q21 — Rectifiers & Filters · hard · numerical
A full-wave rectifier has a peak output current of $10\text{ mA}$. Its DC output current is approximately:
A. $6.37\text{ mA}$ ✓ Correct
B. $3.18\text{ mA}$
C. $5\text{ mA}$
D. $10\text{ mA}$
Solution: $I_{dc} = \dfrac{2I_m}{\pi} = \dfrac{20}{3.1416} \approx 6.37\text{ mA}$.