Operational amplifier or op-amps is a fundamental building block in modern electronic circuits. It is a versatile and widely used component that enables amplification, filtering, and signal conditioning of analog signals. Its wide range of advantages makes it an indispensable tool in audio and video equipment, instrumentation, and control systems, among other applications. At its core, an op-amp operates as a differential amplifier that amplifies the difference between two input voltages. The output voltage is proportional to the input voltage difference and is determined by the op amp’s internal circuitry. With high and low output impedance, op amps are ideal for interfacing with other electronic components. The most basic op amp circuit comprises three terminals: the non-inverting input (+), the inverting input (-), and the output (O). When a voltage is applied to the non-inverting input, the op-amp amplifies it and outputs a voltage proportional to that input. When a voltage is applied to the inverting input, the op-amp inverts it and outputs a voltage proportional to that input. The output voltage of an op-amp can swing between its positive and negative power supply rails, which typically range from +/-5V to +/-15V. Op amps can be utilized in various configurations, from simple voltage amplifiers to complex feedback systems. Standard op-amp configurations include the non-inverting amplifier, the inverting amplifier, the voltage follower, and the differential amplifier. Each configuration setting has its unique characteristics and applications. Overall, op-amps are crucial in modern electronic circuits, enabling precise signal amplification and conditioning across many industries. Whether one is a hobbyist or a professional engineer, understanding op amps is essential for designing and building electronic circuits.

In this post Electrical Engineering Online shares Objective Electrical MCQ Questions on Operational Amplifier.

## What is the primary function of an operational amplifier (op amp)

What is the primary function of an operational amplifier (op amp)?

- To amplify signals
- To generate electrical power
- To store digital data
- To convert analog to digital signals

Correct Answer: 1. To amplify signals

**Explanation:** The primary function of an op-amp is to amplify signals, making it a versatile building block in electronic circuits.

## What is the ideal voltage gain of an op-amp

What is the ideal voltage gain of an op-amp?

- Infinite
- Zero
- Negative
- Variable

Correct Answer: 1. Infinite

**Explanation:** In an ideal scenario, an op amp has infinite voltage gain, which means it can amplify input signals to any desired level.

## What is the input impedance of an ideal op amp

What is the input impedance of an ideal op amp?

- Zero
- Infinite
- Negative
- Variable

Correct Answer: 2. Infinite

**Explanation:** An ideal op amp has infinite input impedance, meaning it draws no current from the input signal source.

## What is the output impedance of an ideal op amp

What is the output impedance of an ideal op amp?

- Zero
- Infinite
- Negative
- Variable

Correct Answer: 1. Zero

**Explanation:** An ideal op amp has zero output impedance, allowing it to drive any load without signal loss.

## What does negative feedback do in an op-amp circuit

What does negative feedback do in an op-amp circuit?

- Increases the gain of the op-amp
- Decreases the gain of the op-amp
- Stabilizes the op amp’s performance
- Increases noise in the circuit

Correct Answer: 3. Stabilizes the op amp’s performance

**Explanation:** Negative feedback in an op-amp circuit helps stabilize its performance by reducing distortion, increasing bandwidth, and improving linearity.

## What is the symbol used to represent an op-amp in circuit diagrams

What is the symbol used to represent an op-amp in circuit diagrams?

- Triangle
- Square
- Circle
- Diamond

Correct Answer: 1. Triangle

**Explanation:** An op amp is typically represented by a triangle symbol in circuit diagrams.

## Which pin of an 741 op amp 8-pin is the inverting input

Which pin of an 741 op amp 8-pin is the inverting input

- PIN 1
- PIN 2
- PIN 3
- PIN 4

Correct Answer: 2. PIN 2

**Explanation:** The inverting input of an op-amp is typically labeled with a minus (-) sign and is used in negative feedback configurations.

## Which pin of an 741 op amp 8-pin is the non-inverting input

Which pin of an 741 op amp 8-pin is the non-inverting input

- PIN 1
- PIN 2
- PIN 3
- PIN 4

Correct Answer: 3. PIN 3

**Explanation:** The non-inverting input of an op-amp is typically labeled with a plus (+) sign and is used in positive feedback configurations.

## What is the gain equation for an inverting amplifier configuration

What is the gain equation for an inverting amplifier configuration?

- Gain = (Vout / Vin)
- Gain = -(Rf / Rin)
- Gain = (Rf / Rin)
- Gain = (Vin / Vout)

Correct Answer: 2. Gain = -(Rf / Rin)

**Explanation:** Gain = -(Rf / Rin) gives the gain equation for an inverting amplifier configuration, where Rf is the feedback resistor, and Rin is the input resistor.

## What is the gain equation for a non-inverting amplifier configuration

What is the gain equation for a non-inverting amplifier configuration?

- Gain = (Vout / Vin)
- Gain = -(Rf / Rin)
- Gain = (Rf /Rin)
- Gain = (Vin / Vout)

Correct Answer: 3. Gain = (Rf / Rin)

**Explanation:** The gain equation for a non-inverting amplifier configuration is given by Gain = (1 + (Rf / Rin)), where Rf is the feedback resistor, and Rin is the input resistor.

## What is the voltage at the inverting input of an op-amp in a negative feedback configuration

What is the voltage at the inverting input of an op-amp in a negative feedback configuration?

- Equal to the input voltage
- Equal to the output voltage
- Zero volts
- Undefined

Correct Answer: 3. Zero volts

**Explanation:** In a negative feedback configuration, the voltage at the inverting input of an op-amp is virtually zero due to the action of the op-amp trying to maintain the inputs at the same voltage.

## What is the purpose of the bypass capacitor in an op-amp circuit

What is the purpose of the bypass capacitor in an op-amp circuit?

- To increase the voltage gain
- To provide negative feedback
- To stabilize the power supply
- To filter out high-frequency noise

Correct Answer: 4. To filter out high-frequency noise

**Explanation:** The bypass capacitor filters out high-frequency noise and provides a stable DC bias voltage for the op-amp circuit.

## Which configuration provides a phase shift of 180 degrees between the input and output of an op-amp

Which configuration provides a phase shift of 180 degrees between the input and output of an op-amp?

- Inverting amplifier
- Non-inverting amplifier
- Integrator
- Differentiator

Correct Answer: 1. Inverting amplifier

**Explanation:** The inverting amplifier configuration provides a phase shift of 180 degrees between the input and output of an op-amp.

## What is the purpose of the input offset voltage compensation in an op-amp

What is the purpose of the input offset voltage compensation in an op-amp?

- To eliminate noise in the circuit
- To adjust the gain of the op-amp
- To minimize the input offset voltage
- To provide power to the op-amp

Correct Answer: 3. To minimize the input offset voltage

**Explanation:** Input offset voltage compensation is used to minimize the input offset voltage, which is a small voltage difference between an op-amp’s inverting and non-inverting inputs.

## What is the output voltage range of an op-amp powered by a single-ended power supply

What is the output voltage range of an op-amp powered by a single-ended power supply?

- Equal to the supply voltage
- Greater than the supply voltage
- Less than the supply voltage
- Zero volts

Correct Answer: 3. Less than the supply voltage

**Explanation:** The output voltage range of an op-amp powered by a single-ended power supply is limited and typically less than the supply voltage.

## What is the purpose of a voltage follower (buffer) circuit using an op amp

What is the purpose of a voltage follower (buffer) circuit using an op amp?

- To amplify the input voltage
- To provide isolation between two circuits
- To provide a high input impedance
- To provide a low output impedance

Correct Answer: 4. To provide a low output impedance

**Explanation:** An op-amp voltage follower circuit provides low output impedance, allowing it to drive loads without affecting the input signal.

## What is the primary advantage of using a rail-to-rail op amp

What is the primary advantage of using a rail-to-rail op amp?

- Higher voltage gain
- Lower power consumption
- Larger output voltage range
- Improved frequency response

Correct Answer: 3. Larger output voltage range

**Explanation:** A rail-to-rail op-amp allows the output voltage to reach closer to the power supply voltages, resulting in a larger output voltage range.

## Which op amp configuration is commonly used to perform mathematical operations, such as addition and subtraction

Which op amp configuration is commonly used to perform mathematical operations, such as addition and subtraction?

- Inverting amplifier
- Summing amplifier
- Integrator
- Differentiator

Correct Answer: 2. Summing amplifier

**Explanation:** The summing amplifier configuration is commonly used to perform mathematical operations, such as addition and subtraction, by summing multiple input voltages with different gain values.

## What is the purpose of a comparator circuit using an op amp

What is the purpose of a comparator circuit using an op amp?

- To amplify the input voltage
- To provide negative feedback
- To compare two input voltages and generate a digital output
- To stabilize the power supply

Correct Answer: 3. To compare two input voltages and generate a digital output

**Explanation:** An op-amp comparator circuit compares two input voltages and generates a digital output based on their relative magnitudes.

## What is the function of the feedback resistor in an op-amp circuit

What is the function of the feedback resistor in an op-amp circuit?

- To set the input impedance
- To set the output impedance
- To provide negative feedback
- To increase the gain

Correct Answer: 3. To provide negative feedback

**Explanation: **The feedback resistor in an op-amp circuit is used to provide negative feedback, which stabilizes the circuit and controls the overall gain of the op-amp