Electronics MCQs Question and Answer in Engineering Physics

51

In one of the following circuits, negative feedback does not operate for a negative input. Which one is it? The op-amps are running from ±15 V supplies.

A)

B)

C)

D)

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Answer & Solution

Answer: Option C

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52

Calculate the collector voltage (V_C) of the transistor circuit as shown in the figure.
[ Given, α = 0.96, l_CBO = 20 μA, V_BE = 0.3 V, R_B = 100 k$$\Omega $$, V_CC = +10 V and R_C = 2.2 k$$\Omega $$ ]
Electronics mcq question image

A) 3.78 V B) 3.82 V C) 4.72 V D) 9.7 V

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Answer & Solution

Answer: Option C

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53

In order to obtain a solution of the differential equation $$\frac{{{d^2}V}}{{d{t^2}}} - 2\frac{{dV}}{{dt}} + {V_1} = 0,$$ involving voltages V(t) and V₁, an operational amplifier (op-amp) circuit would require at least

A) two op-amp integrators and one op-amp adder B) two op-amp differentiators and one op-amp adder C) one op-amp integrator and one op-amp adder D) one op-amp integrator and one op-amp differentiator and one op-amp adder

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Answer & Solution

Answer: Option A

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54

The tank circuit of a Hartley oscillator is shown in the figure. If M is the mutual inductance between the inductors, the oscillation frequency is
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A) $$\frac{1}{{2\pi \sqrt {\left( {{L_1} + {L_2} + 2M} \right)C} }}$$ B) $$\frac{1}{{2\pi \sqrt {\left( {{L_1} + {L_2} - 2M} \right)C} }}$$ C) $$\frac{1}{{2\pi \sqrt {\left( {{L_1} + {L_2} + M} \right)C} }}$$ D) $$\frac{1}{{2\pi \sqrt {\left( {{L_1} + {L_2} - M} \right)C} }}$$

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Answer & Solution

Answer: Option A

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55

An avalanche effect is observed in a diode when

A) the forward voltage is less than the breakdown voltage B) the forward voltage exceeds the breakdown voltage C) the reverse voltage exceeds the breakdown voltage D) the diode is heavily doped and forward biased

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Answer & Solution

Answer: Option C

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56

A piece of semiconducting material is introduced into a circuit. If the temperature of the material is raised, the circuit current will

A) increase B) remain the same C) decrease D) cease to flow

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Answer & Solution

Answer: Option A

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57

The voltage resolution of a 12-bit Digital to Analog Converter (DAC), whose output varies from -10 V to +10 V, is approximately

A) 1 mV B) 5 mV C) 20 mV D) 100 mV

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Answer & Solution

Answer: Option C

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58

For an intrinsic semiconductor, $$m_e^ * $$ and $$m_h^ * $$ are respectively, the effective masses of electrons and holes near the corresponding band edges. At a finite temperature, the position of the Fermi level

A) depends on $$m_e^ * $$ but not on $$m_h^ * $$ B) depends on $$m_h^ * $$ but not on $$m_e^ * $$ C) depends on both $$m_e^ * $$ and $$m_h^ * $$ D) depends neither on $$m_e^ * $$ nor on $$m_h^ * $$

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Answer & Solution

Answer: Option C

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59

Which of the following statements is correct for a common emitter amplifier circuit?

A) The output is taken from the emitter B) There is 180° phase shift between input and output voltages C) There is no phase shift between input and output voltages D) Both p-n junctions are forward biased

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Answer & Solution

Answer: Option B

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60

Consider the following circuit:
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