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 108 of 158
- A. negligible input resistance and high output resistance
- B. high input resistance and low output resistance
- C. medium input resistance and high output resistance
- D. low input resistance as well as output resistance
Explanation: A common-emitter transistor stage has moderate input resistance and relatively high output resistance, along with useful voltage and…
Correct answer: medium input resistance and high output resistance- A. doping of base
- B. size of emitter
- C. rating of transistor
- D. temperature
Explanation: Transistor leakage current is strongly temperature-dependent and increases significantly as temperature rises.
Correct answer: temperature- A. Increase in both input & output impedances
- B. Decreases in both input & output impedances
- C. Increase in input impedance & decreases in output impedance
- D. Decrease in input impedance & increase in output impedance
Explanation: Voltage-series feedback mixes the feedback voltage in series at the input, increasing input impedance, and samples output voltage in…
Correct answer: Increase in input impedance & decreases in output impedance- A. resistor between source and load
- B. inductor between source and load
- C. capacitor between source and load
- D. either A. or B.
Explanation: A coupling capacitor passes AC while blocking DC, so it prevents a DC return path between the source and load.
Correct answer: capacitor between source and load- A. gm r0
- B. gm / r0
- C. gm rπ
- D. gm /rπ
Explanation: For a BJT, the small-signal current gain is approximately β = gm rπ, since gm relates collector current to base-emitter voltage and rπ…
Correct answer: gm rπ- A. 1/11KΩ
- B. 1/5KΩ
- C. 5KΩ
- D. 11KΩ
Explanation: Current-shunt feedback reduces input resistance by the factor 1 + Aβ. Here 1 + Aβ = 1 + 50(0.2) = 11, so the new input resistance is 1…
Correct answer: 1/11KΩ- A. 23dB
- B. 25dB
- C. 46dB
- D. 50dB
Explanation: The common-mode rejection ratio in decibels is the differential voltage gain minus the common-mode voltage gain: CMRR = 48 − 2 = 46 dB.
Correct answer: 46dB- A. CB arrangement with output shorted
- B. CC arrangement with output shorted
- C. CE arrangement with output shorted
- D. None of the above
Explanation: In the CE h-parameter model, h_ie is the input impedance measured with the output terminals short-circuited.
Correct answer: CE arrangement with output shorted- A. The same as for CB
- B. The same as for CC
- C. Different from that in CB
- D. None of the above
Explanation: Although every transistor configuration uses four h parameters, their numerical values depend on whether the circuit is CB, CE, or CC.
Correct answer: Different from that in CB- A. Voltage gain
- B. Current gain
- C. Input impedance
- D. None of the above
Explanation: The parameter h_fe is the forward current gain in the common-emitter configuration with the output port short-circuited.
Correct answer: Current gain- A. May or may not change
- B. Do not change
- C. Also change
- D. None of the above
Explanation: Transistor h parameters depend on operating conditions, including temperature, because temperature changes carrier behavior and junction…
Correct answer: Also change- A. Also change
- B. Do not change
- C. May or may not change
- D. None of the above
Explanation: h parameters are small-signal quantities evaluated at a particular bias or operating point.
Correct answer: Also change- A. Mho
- B. Ohm
- C. Farad
- D. None of the above
Explanation: h_ie is an input impedance, defined as a voltage-to-current ratio, so its unit is the ohm.
Correct answer: Ohm- A. Two
- B. Four
- C. Three
- D. None of the above
Explanation: A transistor two-port network has four hybrid parameters: h_i, h_r, h_f, and h_o.
Correct answer: Four- A. Small signals only
- B. Large signals only
- C. Both small and large signals
- D. None of the above
Explanation: A transistor can be linearized around its bias point only for small signal variations.
Correct answer: Small signals only- A. Large signals only
- B. Small signals only
- C. Both small and large signals
- D. None of the above
Explanation: The h-parameter equivalent circuit is obtained by linearizing the transistor around its operating point, so it is accurate for small…
Correct answer: Small signals only- A. Mixed
- B. Single
- C. Unique
- D. None of the above
Explanation: Hybrid means mixed or made from different types. In transistor h parameters, the term refers to the mixture of impedance, admittance…
Correct answer: Mixed2158. In order to determine hfe and hie parameters of a transistor, __________ is an a.c. short-circuited?
- A. Input
- B. Output
- C. Input as well as output
- D. None of the above
Explanation: For h_ie and h_fe, the output voltage is set to zero, which means the output port is a.c. short-circuited.
Correct answer: Output- A. Hie
- B. Hoe
- C. Hre
- D. None of the above
Explanation: In the common-emitter arrangement, h_ie represents the input impedance when the output is a.c. short-circuited.
Correct answer: Hie- A. 50 KHz
- B. 100KHz
- C. 1000/17 KHz
- D. 1000/7.07 KHz
Explanation: A 20 dB voltage gain corresponds to a voltage gain of 10, since 20 log₁₀(A_v) = 20. Thus the bandwidth is approximately 1 MHz/10 = 100 kHz.
Correct answer: 100KHz