Free Electronics and Devices MCQs with Answers

• A. 10.9 V
• B. 1.09 V
• C. 1.1 V
• D. 12 V

Explanation: At resonance, the inductive and capacitive reactances cancel, so only the resistances remain: 120 + 12 = 132 Ω.

• A. 1.1 mV
• B. 11.1 mV
• C. 111 mV
• D. 200 mV

Explanation: At series resonance, the ideal reactances cancel, leaving the coil winding resistance of 4 Ω in the output branch.

• A. 3.5 kHz
• B. 0 Hz
• C. 0 Hz to 3.5 kHz
• D. 7 kHz

Explanation: A low-pass filter passes frequencies from dc, or 0 Hz, up to its cutoff frequency. Therefore its passband is 0 Hz to 3.5 kHz.

• A. is 7 kHz
• B. is 10 kHz
• C. is 12 kHz
• D. cannot be determined

Explanation: For the usual filter approximation, bandwidth equals fH − fL and the resonant frequency is the midpoint: fL = 14 − 4/2 = 12 kHz.

• A. nonconductor
• B. battery
• C. conductor
• D. microwaveElectronic Components

Explanation: A battery converts stored chemical energy into electrical energy and supplies it to an external circuit.

• A. 60 db
• B. 30 db
• C. 120 db
• D. 600 dbTry Prep Courses

Explanation: Voltage gain in decibels is 20 log10(Av). For a gain of 1000, this gives 20 log10(1000) = 20 × 3 = 60 dB.

• A. Resonant
• B. Sideband
• C. 3 db
• D. None of the above

Explanation: At either cutoff frequency, the amplifier output power falls to half its midband value, corresponding to a voltage gain decrease of about…

• A. Changes in temperature cause thermal instability
• B. Circuit becomes heavy and costly
• C. It becomes difficult to bias the circuit
• D. None of the above

Explanation: Direct coupling passes dc as well as the signal, so temperature changes can shift transistor operating points and accumulate from stage to…

• A. More than
• B. The same as
• C. Less than
• D. Data insufficient

Explanation: Each cascaded amplifier stage contributes high- and low-frequency limitations, narrowing the overall bandwidth of a multistage amplifier.

• A. 5 db
• B. 2 db
• C. 10 db
• D. 3 dbTry Prep Courses

Explanation: For power gain, the change in decibels is 10 log10(P2/P1). Halving the power gives 10 log10(1/2) ≈ -3 dB, so the gain falls by about 3 dB.

• A. RC coupling
• B. Transformer coupling
• C. Direct coupling
• D. None of the aboveCompare Power Rates

Explanation: RC coupling is commonly used in the voltage-amplifier stages because it is inexpensive and gives good voltage gain with a reasonably flat…

• A. 30 db
• B. 60 db
• C. 120 db
• D. 600 db

Explanation: Power gain in decibels is 10 log10(Ap), so 10 log10(1,000,000) = 10×6 = 60 dB.

• A. Step up
• B. Step down
• C. Same turn ratio
• D. None of the above

Explanation: A transistor collector generally has relatively high impedance, while the load may be low impedance.

• A. 600 db
• B. 24 db
• C. 14 db
• D. 27 db

Explanation: Decibel gains of cascaded amplifier stages add directly: 10 + 5 + 12 = 27 dB.

• A. Large
• B. Very large
• C. Small
• D. None of the above

Explanation: Transformer coupling is especially useful when a high-resistance amplifier output must drive a small-resistance load, such as a…

• A. RC
• B. Transformer
• C. Direct
• D. None of the above

Explanation: Direct coupling passes signals down to zero frequency because it has no coupling capacitor or transformer to introduce a low-frequency…

• A. Amplifier level output is kept constant
• B. Amplifier frequency is held constant
• C. Generator frequency is held constant
• D. Generator output level is held constantDiscover Home Audio

Explanation: To plot an amplifier’s frequency response, the generator output level is kept constant while its frequency is varied and the amplifier…

• A. To pass d.c. between the stages
• B. Not to attenuate the low frequencies
• C. To dissipate high power
• D. None of the aboveHire Civil Engineers

Explanation: The coupling capacitor must have sufficiently low reactance at the lowest signal frequency so that it does not attenuate low-frequency…

• A. RC
• B. Transformer
• C. Direct
• D. None of the aboveCompare Local Schools

Explanation: Direct coupling is used for DC amplification because it passes both the signal and its DC component from one stage to the next.

• A. In db
• B. In volts
• C. As a number
• D. None of the aboveGet Study Guides

Explanation: Voltage gain is commonly expressed in decibels using 20 log10(Vo/Vi), which conveniently represents very large gain or attenuation ratios.