250+ TOP MCQs on Inductor Filters and Answers

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Electronic Devices and Circuits Multiple Choice Questions on “Inductor Filters”.

1. What is the effect of an inductor filter on a multi frequency signal?
A. Dampens the AC signal
B. Dampens the DC signal
C. To reduce ripples
D. To change the current
Answer: A
Clarification: Presence of inductor usually dampens the AC signal. Due to self induction induces opposing EMF or changes in the current.

2. The ripple factor (ϒ) of inductor filter is_________
A. ϒ = RZ3/√2ωL
B. ϒ = RZ/3√2ωL
C. ϒ = RZ3√2/ωL
D. ϒ = RZ3/√2ωL
Answer: B
Clarification: Ripple factor will decrease when L is increased and RL. Inductor has a higher dc resistance. It depends on property of opposing the change of direction of current.

3. The inductor filter gives a smooth output because_________
A. It offers infinite resistance to ac components
B. It offers infinite resistance to dc components
C. Pulsating dc signal is allowed
D. The ac signal is amplified
Answer: A
Clarification: The inductor does not allow the ac components to pass through the filter. The main purpose of using an inductor filter is to avoid the ripples. By using this property, the inductor offers an infinite resistance to ac components and gives a smooth output.

4. A full wave rectifier with a load resistance of 5KΩ uses an inductor filter of 15henry. The peak value of applied voltage is 250V and the frequency is 50 cycles per seconC. Calculate the dc load current.
A. 0.7mA
B. 17mA
C. 10.6mA
D. 20mA
Answer: C
Clarification: For a rectifier with an inductor filter,
VDC=2Vm/π, Idc=VDC/RL=2Vm/RLπ
IDC=2*250/(3.14*15*103)=10.6mA.

5. The output of a rectifier is pulsating because_________
A. It has a pulse variations
B. It gives a dc output
C. It contains both dc and ac components
D. It gives only ac components
Answer: C
Clarification: For any electronic devices, a steady dc output is requireC. The filter is used for this purpose. The ac components are removed by using a filter.

6. A dc voltage of 380V with a peak ripple voltage not exceeding 7V is required to supply a 500Ω loaC. Find out the inductance requireC.
A. 10.8henry
B. 30.7henry
C. 28.8henry
D. 15.4henry
Answer: C
Clarification: Given the ripple voltage is 7V. So, 7=1.414VRMS
ϒ=VRMS/VDC=4.95/380=0.0130. ϒ=1/3√2(RL/Lω)
So, L=28.8henry.

7. The inductor filter should be used when RL is consistently small because_________
A. Effective filtering takes place when load current is high
B. Effective filtering takes place when load current is low
C. Current lags behind voltage
D. Current leads voltage
Answer: A
Clarification: When RLis infinite, the ripple factor is 0.471. This value is close to that of a rectifier. So, the resistance should be small.

8. The output voltage VDC for a rectifier with inductor filter is given by_________
A. (2Vm/π)-IDCR
B. (2Vm/π)+IDCR
C. (2Vmπ)-IDCR
D. (2Vmπ)+IDCR
Answer: A
Clarification: The inductor with high resistance can cause poor voltage regulation. The choke resistance, the resistance of half of transformer secondary is not negligible.

9. What causes to decrease the sudden rise in the current for a rectifier?
A. the electrical energy
B. The ripple factor
C. The magnetic energy
D. Infinite resistance
Answer: C
Clarification: When the output current of a rectifier increases above a certain value, magnetic energy is stored in the inductor. This energy tends to decrease the sudden rise in the current. This also helps to prevent the current to fall down too much.

10. A full wave rectifier with a load resistance of 5KΩ uses an inductor filter of 15henry. The peak value of applied voltage is 250V and the frequency is 50 cycles per seconC. Calculate the ripple factor (ϒ).
A. 0.1
B. 0.6
C. 0.5
D. 0.4
Answer: D
Clarification: ϒ=IAC/IDC, IAC=2√2Vm/3π(RL2+4ω2L2)1/2
By putting the values, IAC=4.24Ma. VDC=2Vm/π, IDC=VDC/RL=2Vm/RL π
IDC=2*250/(3.14*15*103)=10.6mA. ϒ=4.24/10.6=0.4.