Multistage Transistor Amplifiers MCQs with Explanations

Correct Answer: Option C — 68 W Explanation: Human hearing perceives loudness on a logarithmic scale . Therefore, a noticeable increase in sound output requires a significant increase in the actual power of the audio system. The change in sound power level is calculated using: Change in dB = 10 × log₁₀(P₂/P₁) Given: Initial power, P₁ = 18 W New power, P₂ = 68 W Therefore: Change in dB = 10 × log₁₀(68/18) = 10 × log₁₀(3.78) ≈ 10 × 0.577 ≈ 5.77 dB A 3 dB increase corresponds to approximately a doubling of sound power . Since increasing the power from 18 W to 68 W produces an increase of approximately 5.77 dB , the change in output would be clearly noticeable. Option A — 2 W: This is a decrease in power, so the sound output would decrease. Option B — 6 W: This is also a decrease in power, so the sound would become quieter. Option C — 68 W: This increases the power from 18 W to 68 W, producing approximately a 5.77 dB increase . Hence, this is the correct option. Option D — None of the above: Incorrect because 68 W satisfies the requirement in the context of the question. Remember for Exams: 3 dB increase ≈ 2× power . The relationship between power and decibels is ΔdB = 10 log₁₀(P₂/P₁) . Final Answer: Option C — 68 W

Human ear response is logarithmic is the correct answer to “The gain of an amplifier is expressed in db because ___________”. This question is standard in competitive examination syllabi for Multistage Transistor Amplifiers.

Electrical size of coupling capacitor becomes very large is the correct answer to “RC coupling is not used to amplify extremely low frequencies because”. This question is standard in competitive examination syllabi for Multistage Transistor Amplifiers.

66 db is the correct answer to “A current amplification of 2000 is a gain of ___________”. This question is standard in competitive examination syllabi for Multistage Transistor Amplifiers.

3 db is the correct answer to “If the power level of an amplifier reduces to half, the db gain will fall by .”. This question is standard in competitive examination syllabi for Multistage Transistor Amplifiers.

Changes in temperature cause thermal instability is the correct answer to “The number of stages that can be directly coupled is limited because”. This question is standard in competitive examination syllabi for Multistage Transistor Amplifiers.

RC coupling is the correct answer to “In the initial stages of a multistage amplifier, we use ___________”. This question is standard in competitive examination syllabi for Multistage Transistor Amplifiers.

More than one stages is the correct answer to “A radio receiver has ___________ of amplification”. This question is standard in competitive examination syllabi for Multistage Transistor Amplifiers.

Voltage is the correct answer to “RC coupling is used for ___________ amplification”. This question is standard in competitive examination syllabi for Multistage Transistor Amplifiers.

Power is the correct answer to “Transformer coupling is used for ___________ amplification”. This question is standard in competitive examination syllabi for Multistage Transistor Amplifiers.

Half-power is the correct answer to “The lower and upper cut off frequencies are also called ___________ frequencies”. This question is standard in competitive examination syllabi for Multistage Transistor Amplifiers.

3 db is the correct answer to “The upper or lower cut off frequency is also called ___________ frequency”. This question is standard in competitive examination syllabi for Multistage Transistor Amplifiers.

Direct is the correct answer to “The best frequency response is of ___________ coupling”. This question is standard in competitive examination syllabi for Multistage Transistor Amplifiers.

40% is the correct answer to “1 db corresponds to ___________ change in voltage or current level”. This question is standard in competitive examination syllabi for Multistage Transistor Amplifiers.

Is constant is the correct answer to “In an RC coupled amplifier, the voltage gain over mid-frequency range ___________”. This question is standard in competitive examination syllabi for Multistage Transistor Amplifiers.

Not to attenuate the low frequencies is the correct answer to “In an RC coupling scheme, the coupling capacitor CC must be large enough ___________”. This question is standard in competitive examination syllabi for Multistage Transistor Amplifiers.

Economy is the correct answer to “An advantage of RC coupling scheme is the ___________”. This question is standard in competitive examination syllabi for Multistage Transistor Amplifiers.

Direct is the correct answer to “When a multistage amplifier is to amplify d.c. signal, then one must use coupling”. This question is standard in competitive examination syllabi for Multistage Transistor Amplifiers.

60 db is the correct answer to “A gain of 1,000,000 times in power is expressed by ___________”. This question is standard in competitive examination syllabi for Multistage Transistor Amplifiers.

60 db is the correct answer to “A gain of 1000 times in voltage is expressed by ___________”. This question is standard in competitive examination syllabi for Multistage Transistor Amplifiers.

26% is the correct answer to “1 db corresponds to ___________ change in power level”. This question is standard in competitive examination syllabi for Multistage Transistor Amplifiers.

8 db is the correct answer to “An amplifier receives 0.1 W of input signal and delivers 15 W of signal power. What is the power gain in db”. This question is standard in competitive examination syllabi for Multistage Transistor Amplifiers.

Transformer coupling is the correct answer to “The final stage of a multistage amplifier uses ___________”. This question is standard in competitive examination syllabi for Multistage Transistor Amplifiers.

Generator output level is held constant is the correct answer to “In obtaining the frequency response curve of an amplifier, the ___________”. This question is standard in competitive examination syllabi for Multistage Transistor Amplifiers.

27 db is the correct answer to “If a three-stage amplifier has individual stage gains of 10 db, 5 db and 12 db, then total gain in db is ___________”. This question is standard in competitive examination syllabi for Multistage Transistor Amplifiers.

10 µF is the correct answer to “In RC coupling, the value of coupling capacitor is about ___________”. This question is standard in competitive examination syllabi for Multistage Transistor Amplifiers.

Frequency distortion is the correct answer to “The ear is not sensitive to ___________”. This question is standard in competitive examination syllabi for Multistage Transistor Amplifiers.

Low efficiency is the correct answer to “RC coupling is generally confined to low power applications because of”. This question is standard in competitive examination syllabi for Multistage Transistor Amplifiers.

Transformer is the correct answer to “___________ coupling provides the maximum voltage gain”. This question is standard in competitive examination syllabi for Multistage Transistor Amplifiers.

5 mV is the correct answer to “The output of a microphone is rated at -52 db. The reference level is 1V under specified conditions. What is the output voltage of this microphone under the same sound conditions”. This question is standard in competitive examination syllabi for Multistage Transistor Amplifiers.

More than is the correct answer to “The bandwidth of a single stage amplifier is ___________ that of a multistage amplifier”. This question is standard in competitive examination syllabi for Multistage Transistor Amplifiers.

Small is the correct answer to “Transformer coupling is generally employed when load resistance is”. This question is standard in competitive examination syllabi for Multistage Transistor Amplifiers.

Separate bias of one stage from another is the correct answer to “The purpose of RC or transformer coupling is to ___________”. This question is standard in competitive examination syllabi for Multistage Transistor Amplifiers.

Poor is the correct answer to “The frequency response of transformer coupling is ___________”. This question is standard in competitive examination syllabi for Multistage Transistor Amplifiers.

Step down is the correct answer to “In transistor amplifiers, we use ___________ transformer for impedance matching”. This question is standard in competitive examination syllabi for Multistage Transistor Amplifiers.

Loading effect of the next stage is the correct answer to “The total gain of a multistage amplifier is less than the product of the gains of individual stages due to ___________”. This question is standard in competitive examination syllabi for Multistage Transistor Amplifiers.

In db is the correct answer to “In practice, voltage gain is expressed ___________”. This question is standard in competitive examination syllabi for Multistage Transistor Amplifiers.