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OP-AMP Circuits

Study 24 Electrical Engineering MCQs with correct answers and explanations.

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11Electrical EngineeringMedium

For an ideal op-amp, which of the following is true?

AThe output resistance is zero

BThe current from output terminal is zero

CThe differential voltage across the input terminals is zero

DThe current into the input terminals is zero

Correct answer

B. The current from output terminal is zero

Explanation

The correct answer is The current from output terminal is zero.

12Electrical EngineeringMedium

Differential amplifiers are used in________?

AVoltage regulators

BVoltage followers

CBuffers

DInstrumentation amplifiers

Correct answer

D. Instrumentation amplifiers

Explanation

The correct answer is Instrumentation amplifiers.

13Electrical EngineeringMedium

A 741-Type OP-AMP has a gain-bandwith product of 1MHz. A non-inverting amplifier using this opamp & having a voltage gain of 20db will exhibit -3db bandwidth of________?

A1000/7.07KHz

B100KHz

C50KHz

D1000/17KHz

Correct answer

C. 50KHz

Explanation

The correct answer is 50KHz.

14Electrical EngineeringMedium

The closed-loop voltage gain of an inverting amplifier equal to________?

AThe input resistance

BThe feedback resistance divided by the input resistance

CThe ratio of the input resistance to feedback resistance

DThe open-loop voltage gain

Correct answer

B. The feedback resistance divided by the input resistance

Explanation

The correct answer is The feedback resistance divided by the input resistance.

15Electrical EngineeringMedium

For an op-amp having differential gain Av and common-mode gain Ac the CMRR is given by________?

AAv + Ac

BAc / Av

C1 + Av / AC.

Correct answer

A. Av + Ac

Explanation

The correct answer is Av + Ac.

16Electrical EngineeringMedium

Hysteresis is desirable in Schmitt-trigger, because________?

AEnergy is to be stored/discharged in parasitic capacitances

BEffects of temperature would be compensated

CIt would prevent noise from causing false triggering

DDevices in the circuit should be allowed time for saturation and desaturation

Correct answer

D. Devices in the circuit should be allowed time for saturation and desaturation

Explanation

The correct answer is Devices in the circuit should be allowed time for saturation and desaturation.

17Electrical EngineeringMedium

In the above circuit the current ix is________?

A0.6A

B0.2A

C0.5A

D1/12A

Correct answer

C. 0.5A

Explanation

The correct answer is 0.5A.

18Electrical EngineeringMedium

The output voltage Vo of the above circuit is________?

A-6V

B-0.2V

C-5V

D-1.2V

Correct answer

C. -5V

Explanation

The correct answer is -5V.

19Electrical EngineeringMedium

Which of the following amplifier is used in a digital to analog converter?

AVoltage follower

BSummer

CDifference amplifier

DNon inverter

Correct answer

B. Summer

Explanation

The correct answer is Summer.

20Electrical EngineeringMedium

How many op-amps are required to implement this equationop-amps?

Correct answer

C. 1

Explanation

The correct answer is 1.

For an ideal op-amp, which of the following is true?

AThe output resistance is zero

BThe current from output terminal is zero

CThe differential voltage across the input terminals is zero

DThe current into the input terminals is zero

Correct answer

B. The current from output terminal is zero

Explanation

The correct answer is The current from output terminal is zero.

The closed-loop voltage gain of an inverting amplifier equal to________?

AThe input resistance

BThe feedback resistance divided by the input resistance

CThe ratio of the input resistance to feedback resistance

DThe open-loop voltage gain

Correct answer

B. The feedback resistance divided by the input resistance

Explanation

The correct answer is The feedback resistance divided by the input resistance.

Hysteresis is desirable in Schmitt-trigger, because________?

AEnergy is to be stored/discharged in parasitic capacitances

BEffects of temperature would be compensated

CIt would prevent noise from causing false triggering

DDevices in the circuit should be allowed time for saturation and desaturation

Correct answer

D. Devices in the circuit should be allowed time for saturation and desaturation

Explanation

The correct answer is Devices in the circuit should be allowed time for saturation and desaturation.