All Free Electrical Engineering MCQs with Answers
Every Electrical Engineering question in the bank, across all chapters, each with the correct answer and a written explanation. Free and unlimited, with no account needed.
3,143 questions · page 105 of 158
- A. Minimum
- B. Maximum
- C. Half-way between maximum and minimum
- D. Zero
Explanation: At resonance, the tuned load provides the intended maximum impedance and signal response at its selected frequency.
Correct answer: Maximum- A. Class A
- B. Class C
- C. Class B
- D. None of the above
Explanation: Tuned amplifiers commonly use Class C operation because its high efficiency suits narrowband RF amplification.
Correct answer: Class C- A. The difference frequency is closer to oscillator frequency
- B. Lower frequencies are easier to amplify
- C. Only the difference frequency can be modulated
- D. None of the above
Explanation: The difference frequency is selected as the intermediate frequency because it is lower and can be amplified and filtered conveniently with…
Correct answer: Lower frequencies are easier to amplify- A. Radio frequency
- B. IF
- C. Audio frequency
- D. None of the above
Explanation: A TRF receiver amplifies the incoming signal directly at its radio frequency, with the tuned circuits tracking that frequency.
Correct answer: Radio frequency- A. Amplitude
- B. Frequency
- C. Phase
- D. None of the above
Explanation: Television sound is normally transmitted using frequency modulation, which provides better noise immunity than AM.
Correct answer: Frequency- A. Before the first RF stage
- B. After the first RF stage
- C. After several stages of amplification
- D. None of the above
Explanation: The diode detector is placed after RF and usually IF amplification so that it receives a sufficiently strong modulated signal.
Correct answer: After several stages of amplification- A. Amplitude of the carrier
- B. Frequency of the carrier
- C. Phase of the carrier
- D. May be any of the above
Explanation: Modulation means varying a carrier parameter according to the information signal.
Correct answer: May be any of the above- A. Reception is less noisy
- B. Higher carrier frequency
- C. Smaller bandwidth
- D. Small frequency deviation
Explanation: FM has strong resistance to amplitude noise because the information is carried by frequency changes, and limiting circuits can remove…
Correct answer: Reception is less noisy- A. Using a large number of amplifier stages
- B. Using a push-pull circuit
- C. Obtaining lower fixed intermediate frequency
- D. None of the above
Explanation: A superheterodyne receiver mixes the incoming signal with a local oscillator to produce a lower, fixed intermediate frequency.
Correct answer: Obtaining lower fixed intermediate frequency- A. RF
- B. IF
- C. audio
- D. Before RF
Explanation: Mixing translates the selected station to a fixed intermediate frequency, where sharply tuned IF filters provide most of the receiver's…
Correct answer: IF- A. IF
- B. RF amplifier
- C. Audio amplifier
- D. Detector
Explanation: The IF amplifier is designed for high, stable gain at one fixed frequency, so several cascaded IF stages provide most of the receiver…
Correct answer: IF- A. Sensitivity
- B. Selectivity
- C. Distortion
- D. Fidelity
Explanation: Fidelity describes how accurately a receiver reproduces the entire range of signal frequencies, so equal amplification indicates high…
Correct answer: Fidelity- A. Audio voltage control
- B. Abrupt voltage control
- C. Automatic volume control
- D. Automatic voltage control
Explanation: AVC means automatic volume control, a receiver circuit that adjusts gain as received signal strength changes.
Correct answer: Automatic volume control- A. IF and RF
- B. RF and AF
- C. IF and AF
- D. RF and local oscillator signal
Explanation: The mixer combines the incoming RF signal with the local oscillator signal, producing sum and difference frequencies.
Correct answer: RF and local oscillator signal- A. Phase modulation
- B. Amplitude modulation
- C. Frequency modulation
- D. May be any one of the above
Explanation: Frequency modulation occurs when the instantaneous frequency of the carrier varies according to the modulating signal.
Correct answer: Frequency modulation- A. 455 kHz
- B. 1310 kHz
- C. 1500 kHz
- D. 1520 kHz
Explanation: For the usual high-side injection, the local oscillator is set to signal frequency plus IF: 855 + 455 = 1310 kHz.
Correct answer: 1310 kHz- A. Reduce stray capacitance
- B. Stabilise d.c. bias
- C. Increase the Q of tuned circuit
- D. Reduce noise
Explanation: A ferrite rod increases the inductance and magnetic flux linkage of the coil, allowing a compact tuned antenna with a higher Q and better…
Correct answer: Increase the Q of tuned circuit- A. 20 %
- B. 40 %
- C. 50 %
- D. 10 %
Explanation: Using m = (Amax − Amin)/(Amax + Amin), m = (60 − 40)/(60 + 40) = 0.20. Therefore the percentage modulation is 20%, not 40% or 50%.
Correct answer: 20 %- A. Crystal
- B. Wien-bridge
- C. Phase-shift
- D. Hartley
Explanation: A Hartley oscillator is commonly used as a receiver local oscillator because its tuned LC circuit provides convenient frequency adjustment…
Correct answer: Hartley- A. 50 kW
- B. 5 kW
- C. 8 kW
- D. 25 kW
Explanation: In amplitude modulation, the carrier power remains constant at all modulation depths; only the sideband power changes.
Correct answer: 50 kW