Operational amplifiers (Op-Amps): characteristics and applications MCQs

Q#1: In an ideal operational amplifier, the open-loop gain is:
(A) Zero
(B) 1
(C) Infinite
(D) 1000
Answer: (C) Infinite

Q#2: The input impedance of an ideal operational amplifier is:
(A) Zero
(B) Low
(C) Infinite
(D) Variable
Answer: (C) Infinite

Q#3: The output impedance of an ideal operational amplifier is:
(A) Zero
(B) Low
(C) High
(D) Variable
Answer: (A) Zero

Q#4: The ideal op-amp should have an infinite common-mode rejection ratio (CMRR). This means:
(A) The op-amp can reject all signals
(B) The op-amp will reject both input signals equally
(C) The op-amp rejects common-mode signals completely
(D) The op-amp will have high input impedance
Answer: (C) The op-amp rejects common-mode signals completely

Q#5: The typical input offset voltage of an operational amplifier is:
(A) Zero
(B) Very small (millivolt range)
(C) 1V
(D) Large (greater than 10V)
Answer: (B) Very small (millivolt range)

Q#6: In an ideal op-amp, the voltage difference between the inverting and non-inverting inputs is:
(A) Infinite
(B) Zero
(C) Equal to the input voltage
(D) Dependent on the supply voltage
Answer: (B) Zero

Q#7: The voltage gain of an operational amplifier in an open-loop configuration is:
(A) Constant
(B) Extremely high, but finite
(C) High, but adjustable
(D) Low
Answer: (B) Extremely high, but finite

Q#8: The gain of a non-inverting amplifier is given by the formula:
(A) $1 + frac{R_f}{R_1}$
(B) $frac{R_f}{R_1}$
(C) $1 – frac{R_f}{R_1}$
(D) $frac{R_1}{R_f}$
Answer: (A) $1 + frac{R_f}{R_1}$

Q#9: The primary function of an inverting amplifier is to:
(A) Amplify the input signal without changing the phase
(B) Amplify the input signal with a 180-degree phase shift
(C) Provide voltage buffering
(D) Integrate or differentiate the signal
Answer: (B) Amplify the input signal with a 180-degree phase shift

Q#10: A differential amplifier amplifies the difference between:
(A) Two input signals
(B) A signal and ground
(C) A positive and negative input signal
(D) The signal and the feedback
Answer: (A) Two input signals

Q#11: Which of the following is a common application of an op-amp in a voltage follower configuration?
(A) Amplifying weak signals
(B) Providing impedance matching
(C) Signal mixing
(D) Signal differentiation
Answer: (B) Providing impedance matching

Q#12: In an op-amp-based integrator, the output is the:
(A) Sum of the input signal with respect to time
(B) Derivative of the input signal
(C) Integral of the input signal with respect to time
(D) Input signal multiplied by a constant
Answer: (C) Integral of the input signal with respect to time

Q#13: A differentiator circuit using an op-amp produces an output that is:
(A) Proportional to the input voltage
(B) The integral of the input signal
(C) The derivative of the input signal
(D) Equal to the input signal
Answer: (C) The derivative of the input signal

Q#14: An op-amp-based Schmitt trigger is primarily used for:
(A) Amplifying signals
(B) Filtering noise and providing a clean output
(C) Rectifying AC signals
(D) Integrating signals
Answer: (B) Filtering noise and providing a clean output

Q#15: The ideal voltage gain of an operational amplifier in open-loop configuration is:
(A) Zero
(B) 1
(C) Infinite
(D) 10
Answer: (C) Infinite

Q#16: A negative feedback in an operational amplifier leads to:
(A) A decrease in bandwidth
(B) Increased output impedance
(C) Reduced distortion and stabilization of gain
(D) Increased power consumption
Answer: (C) Reduced distortion and stabilization of gain

Q#17: In an op-amp circuit, when the output voltage is negative and the input signal is positive, this is an example of:
(A) Positive feedback
(B) Negative feedback
(C) Inverting configuration
(D) Non-inverting configuration
Answer: (C) Inverting configuration

Q#18: A voltage comparator using an op-amp is used to:
(A) Compare two input voltages and output a signal indicating the higher voltage
(B) Provide an amplified output signal
(C) Rectify the input AC voltage
(D) Integrate or differentiate the input voltage
Answer: (A) Compare two input voltages and output a signal indicating the higher voltage

Q#19: An op-amp with a high gain is ideal for use in which of the following circuits?
(A) Active filters
(B) Oscillators
(C) High-precision amplifiers
(D) All of the above
Answer: (D) All of the above

Q#20: A practical application of an op-amp in a signal conditioning circuit is:
(A) Voltage regulation
(B) Voltage amplification and filtering
(C) Voltage comparator
(D) High-speed switching
Answer: (B) Voltage amplification and filtering