Free Electronics and Devices MCQs with Answers
758 Electronics and Devices 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.
Last updated
758 questions · page 9 of 38
- A. Remains the same
- B. Decreases
- C. Increases
- D. None of the above
Explanation: For a common-emitter circuit, V_CE is approximately V_CC − I_C R_C. Therefore, with supply voltage and collector resistance fixed…
Correct answer: Decreases- A. Depends upon IC to moderate extent
- B. Is almost independent of IC
- C. Is strongly dependant on IC
- D. None of the above
Explanation: For a conducting transistor, V_BE changes only logarithmically with collector current, so over normal operating ranges it is treated as…
Correct answer: Is almost independent of IC- A. 105 kO
- B. 530 kO
- C. 315 kO
- D. None of the above
Explanation: The base current is I_B = I_C/β = 1 mA/100 = 10 μA, and the base resistor is R_B = (V_CC − V_BE)/I_B = (6 − 0.7)/10 μA = 530 kΩ.
Correct answer: 530 kO- A. Change in ICBO
- B. Change in VCC
- C. Change in the values of circuit resistance
- D. None of the above
Explanation: Temperature rise increases the reverse leakage current I_CBO, which increases collector current and shifts the transistor operating point.
Correct answer: Change in ICBO165. The stabilisation of operating point in potential divider method is provided by_______________?
- A. RE consideration
- B. RC consideration
- C. VCC consideration
- D. None of the above
Explanation: In the voltage-divider bias circuit, R_E provides negative feedback: increased collector or emitter current raises the emitter voltage and…
Correct answer: RE consideration- A. VCE consideration
- B. VBE consideration
- C. IB consideration
- D. None of the above
Explanation: R_C is selected from the desired collector voltage and operating-point condition, using the voltage drop V_RC = I_C R_C and the required…
Correct answer: VCE consideration- A. VBE
- B. 2VBE
- C. 5 VBE
- D. None of the above
Explanation: Applying KVL across the collector-emitter path gives VCE = VCB + VBE. The collector-to-base and base-to-emitter voltages therefore add to…
Correct answer: VBE- A. The same as
- B. More than
- C. Less than
- D. None of the above
Explanation: Collector-feedback bias provides negative feedback: an increase in collector current raises the feedback voltage and opposes the increase.
Correct answer: Less than- A. Remains the same
- B. Is increased
- C. Is decreased
- D. None of the above
Explanation: As temperature rises, leakage current and collector current generally increase, causing a larger voltage drop across the collector…
Correct answer: Is decreased- A. RB (ß+1)
- B. (ß+1)RC
- C. (ß+1)
- D. 1-ß
Explanation: For fixed base-resistor bias, the stability factor is S = 1 + β, commonly written as β + 1.
Correct answer: (ß+1)- A. 2000 O
- B. 1400 O
- C. 800 O
- D. 1600 O
Explanation: Using VCC = VRC + VCE + VE, the emitter voltage is 9 − (2 mA)(2.2 kΩ) − 3 = 1.6 V. Thus RE = VE/IE = 1.6 V/2 mA = 800 Ω.
Correct answer: 800 O- A. High stability factor
- B. Low base current
- C. Many resistors
- D. None of the above
Explanation: Voltage-divider bias is thermally stable, but it requires the divider, collector, and emitter resistors, making it more complex than…
Correct answer: Many resistors- A. The end point
- B. Middle
- C. The maximum current point
- D. None of the above
Explanation: Placing the operating point near the midpoint of the DC load line allows nearly equal maximum swings toward cutoff and saturation.
Correct answer: Middle- A. Cut off point
- B. Quiescent point
- C. Saturation point
- D. None of the above
Explanation: The operating point is the transistor's quiescent point, abbreviated Q-point, representing the zero-signal condition.
Correct answer: Quiescent point- A. 10 IB
- B. 3 IB
- C. 2 IB
- D. 4 IB
Explanation: For good voltage-divider bias stabilisation, the divider current I1 is commonly chosen as at least 10 times the base current IB.
Correct answer: 10 IB- A. Is complicated
- B. Is sensitive to changes in ß
- C. Provides high stability
- D. None of the above
Explanation: In base-resistor bias, the collector current depends strongly on beta through IC approximately equal to beta times IB.
Correct answer: Is sensitive to changes in ß- A. One hundredth
- B. One tenth
- C. One thousandth
- D. One millionth
Explanation: Silicon has much lower minority-carrier leakage than germanium, commonly approximated as about one-thousandth under comparable conditions.
Correct answer: One thousandth- A. 100 µA
- B. 25 µA
- C. 20 µA
- D. 50 µA
Explanation: The stability factor relates the collector-current change to the leakage-current change: S = ΔIC/ΔICBO. Therefore, ΔIC = 50 × 1 μA = 50 μA.
Correct answer: 50 µA- A. 6 mA
- B. mA
- C. 3 mA
- D. 1 mA
Explanation: To allow a 3 mA signal swing without driving the transistor into cutoff, the zero-signal collector current must be at least 3 mA.
Correct answer: 3 mA- A. Base resistor bias
- B. Collector feedback bias
- C. Potential divider bias
- D. None of the above
Explanation: Potential-divider bias provides the best common stabilisation because the divider fixes the base voltage and makes the operating point…
Correct answer: Potential divider bias