# Operational Amplifier And 555 Timer A1 And A3

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| By Pratiksha
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Pratiksha
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Quizzes Created: 2 | Total Attempts: 246
Questions: 10 | Attempts: 113

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• 1.

### Pick all incorrect statements. Analog signals are A. Continuous. B. Easy to process compared to digital signals. C. More immune to Noise compared to digital signals. D. Easily reproducible when compared to digital signals.

• A.

A, B and D

• B.

B, C and D

• C.

B and C

• D.

B and D

D. B and D
Explanation
Analog signals are continuous, making statement A correct. However, statement B is incorrect because digital signals are generally easier to process compared to analog signals. Statement C is also incorrect because digital signals are more immune to noise compared to analog signals. Lastly, statement D is incorrect because digital signals are easily reproducible compared to analog signals.

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• 2.

### Find the gain of the inverting amplifier shown below. Consider R1 = 1kΩ and RF = 10kΩ Assume op-amp is ideal.

• A.

-10

• B.

-10k

• C.

-100

• D.

-1

A. -10
Explanation
The gain of an inverting amplifier is determined by the ratio of the feedback resistor (RF) to the input resistor (R1). In this case, RF is given as 10kΩ and R1 is given as 1kΩ. The gain is calculated as the negative ratio of RF to R1, which is -10. Therefore, the correct answer is -10.

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• 3.

### Open loop gain of an IC 741 is

• A.

2*10^5

• B.

1

• C.

• D.

0

A. 2*10^5
Explanation
The open loop gain of an IC 741 is 2*10^5. This means that when the IC 741 is operating in an open loop configuration, the gain of the amplifier is 2*10^5. This high gain allows the IC 741 to amplify small input signals to a much larger output signal.

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• 4.

### In the application of OP-AMP as an amplifier _____________ feedback is used

• A.

Positive

• B.

No

• C.

Negative

• D.

Series

C. Negative
Explanation
In the application of OP-AMP as an amplifier, negative feedback is used. Negative feedback is a technique where a portion of the output signal is fed back to the input with a phase inversion. This helps in stabilizing the amplifier's gain and reducing distortion. By using negative feedback, the amplifier can have a more accurate and linear response, making it suitable for various applications such as audio amplification and signal conditioning.

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• 5.

### In given circuit Vin = 2 V, R1 = 1KΩ and R2 = 10KΩ.What is the output voltage of an amplifier

• A.

11 V

• B.

-22 V

• C.

22 V

• D.

-20 V

C. 22 V
Explanation
The output voltage of an amplifier can be calculated using the formula Vout = Vin * (1 + (R2/R1)). In this case, Vin is given as 2 V, R1 is 1KΩ, and R2 is 10KΩ. Plugging in these values, we get Vout = 2 * (1 + (10/1)) = 2 * 11 = 22 V. Therefore, the output voltage of the amplifier is 22 V.

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• 6.

### For first order butterworth high pass filter, calculate lower cut off frequency if R=15KΩ and C = 0.01. Also calculate Avf if Rf = 10K Ω and R1 = 5kΩ.

• A.

1061 Hz,3

• B.

1061Hz,2

• C.

1061kHz,3

• D.

1061KHz,2

A. 1061 Hz,3
Explanation
The lower cut-off frequency for a first-order Butterworth high pass filter is determined by the formula: f = 1 / (2πRC). Plugging in the given values of R = 15KΩ and C = 0.01, we can calculate the lower cut-off frequency as f = 1 / (2π * 15KΩ * 0.01) = 1061 Hz.

The Avf (voltage gain) for this filter is determined by the formula: Avf = 1 + (Rf / R1). Plugging in the given values of Rf = 10KΩ and R1 = 5KΩ, we can calculate the Avf as Avf = 1 + (10KΩ / 5KΩ) = 3.

Therefore, the correct answer is 1061 Hz, 3.

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• 7.

### Output produce by an op-amp is 180 degree phase shifted when input is applied to

• A.

Inverting terminal

• B.

Non Inverting terminal

• C.

Both inverting and non inverting terminals

• D.

Common mode

A. Inverting terminal
Explanation
When an input is applied to the inverting terminal of an op-amp, the output produced is 180 degrees out of phase with the input. This means that when the input signal goes positive, the output signal goes negative, and vice versa. This phase shift is a characteristic of the inverting configuration of an op-amp, where the input signal is connected to the inverting terminal and the feedback is applied to the non-inverting terminal.

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• 8.

### Determine closed loop voltage gain of an non inverting amplifier if feedback resistor is 3 times input resistor

• A.

3

• B.

6

• C.

4

• D.

-3

C. 4
Explanation
The closed loop voltage gain of a non-inverting amplifier is determined by the ratio of the feedback resistor to the input resistor. In this case, since the feedback resistor is 3 times the input resistor, the closed loop voltage gain would be 3. However, the given answer is 4, which does not match the expected value. Therefore, the given answer is incorrect and there is no suitable explanation for it.

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• 9.

### Voltage follower is also called as

• A.

Unity gain buffer

• B.

Non inverting amplifier

• C.

Buffer

• D.

Inverting amplifier

A. Unity gain buffer
Explanation
A voltage follower, also known as a unity gain buffer, is an electronic circuit that has a voltage gain of 1. It is called a buffer because it isolates the input from the output, preventing any loading effects. In other words, it replicates the input voltage at the output without amplifying or attenuating it. This is achieved by using an operational amplifier configured in a non-inverting amplifier configuration with a gain of 1. Therefore, the correct answer is unity gain buffer.

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• Current Version
• Mar 20, 2023
Quiz Edited by
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• Jan 28, 2019
Quiz Created by
Pratiksha

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