This set of Electronic Devices and Circuits Multiple Choice Questions & Answers (MCQs) focuses on “The Non Inverting Configuration”.

1. In the non-inverting configuration of operational amplifier

a) The positive terminal is connected to the ground directly

b) The negative terminal is connected to the ground directly

c) The positive terminal is connected to the power source

d) The negative terminal is connected to the power source

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Explanation: Non inverting configuration requires a power source connected to the power source.

2. For ideal non-inverting operational amplifier

a) Input and output resistances are infinite

b) Input resistance is infinite and output resistance is zero

c) Input resistance is zero and output resistance is infinite

d) Input and output resistances are zero

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Explanation: It is an ideal characteristic of the non-inverting op amp.

3. For an ideal non-inverting operational amplifier having finite gain (A), the ratio of output voltage (v_{0}) to input voltage (v_{i}) is (given R_{2} is the feedback resistance)

a) (1+R2/R1)/(1+((1+R2/R1)/A))

b) (R2/R1)/(((1+R2/R1)/A))

c) (1+R2/R1)/(((1+R2/R1)/A))

d) (R2/R1)/(1+((1+R2/R1)/A))

View Answer

Explanation: It is a standard mathematical expression.

4. The gain for an ideal non-inverting operational amplifier is (given R_{2} is the feedback resistance)

a) R_{2}/R_{1} – 1

b) R_{2}/R_{1}

c) -R_{2}/R_{1}

d) R_{2}/R_{1} + 1

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Explanation: It is a standard mathematical expression.

5. While performing an experiment to determine the gain for an ideal operational amplifier having finite gain, a student mistakenly used the equation 1 + R_{2}/R_{1} where R_{2} is the feedback resistance. What is the percentage error in his result? Given A is the finite voltage gain of the ideal amplifier used.

a) (R2/R1)/(A+ R2/R1) X 100%

b) (1+R2/R1)/(A+R2/R1) X 100%

c) (1+R2/R1)/(A+1+R2/R1) X 100%

d) (R2/R1)/(A+1+R2/R1) X 100%

View Answer

Explanation: The correct formula is (1+R2/R1)/(1+((1+R2/R1)/A)).

6. The finite voltage gain of a non-inverting operational amplifier is A and the resistance used is R_{1} and R_{2} in which R_{2} is the feedback resistance. Under what conditions it can one use the expression 1 + R_{2}/R_{1} to determine the gain of the amplifier?

a) A ~ R_{2}/R_{1}

b) A >> R_{2}/R_{1}

c) A << R_{2}/R_{1}

d) None of the mentioned

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Explanation: The formula is valid for the ideal case in which the value of A is infinite, practically it should be very large when compared to R

_{2}/R

_{1}.

7. Which of the following is not true for a voltage follower amplifier?

a) Input voltage is equal to output voltage

b) Input resistance is infinite and output resistance is zero

c) It has 100% negative feedback

d) None of the mentioned

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Explanation: All the statements are false.

8. For designing a non-inverting amplifier with a gain of 2 at the maximum output voltage of 10 V and the current in the voltage divider is to be 10 μA the resistance required are R_{1} and R_{2} where R_{2} is used to provide negative feedback. Then

a) R_{1} = 0.5 MΩ and R_{2} = 0.5 MΩ

b) R_{1} = 0.5 kΩ and R_{2} = 0.5 kΩ

c) R_{1} = 5 MΩ and R_{2} = 5 MΩ

d) R_{1} = 5 kΩ and R_{2} = 5 kΩ

View Answer

Explanation: 1 + R2/R

_{1}= 2 and 10/(R

_{1}+R

_{2}) = 10 μA. Solve for R

_{1}and R

_{2}.

9. It is required to connect a transducer having an open-circuit voltage of 1 V and a source resistance of 1 MΩ to a load of 1-kΩ resistance. Find the load voltage if the connection is done (a) directly and (b) through a unity-gain voltage follower.

a) 1 μV and 1 mV respectively

b) 1 mV and 1 V respectively

c) 0.1 μV and 0.1 mV respectively

d) 0.1 mV and 0.1 V respectively

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Explanation: When a unity gain follower is uses then input signal is equal to output signal. When connected directly, output signal is given by 1 X 1kΩ/1MΩ or 1mV.

10. Consider the figure given below. If the resistance R_{1} is disconnected from the ground and connected to a third power source v_{3}, then expression for the value of

v_{0} is

a) 2v_{1} + 4v_{2} − 3v_{3}

b) 6v_{1} + 8v_{2} − 3v_{3}

c) 6v_{1} + 4v_{2} − 9v_{3}

d) 3v_{1} + 4v_{2} − 3v_{3}

View Answer

Explanation: When a third power source is connected to the resistance of 1kΩ, then also the potential between the two input terminals of op amps remains the same. Using this fact the expression c is obtained.

**Sanfoundry Global Education & Learning Series – Electronic Devices and Circuits.**

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