Understanding Operational Amplifiers Quiz

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

• To amplify voltage signals

• To convert AC to DC

• To store electrical energy

• To measure resistance

Answer explanation

The primary function of an operational amplifier (op-amp) is to amplify voltage signals. It is designed to increase the amplitude of input signals, making it essential in various electronic applications.

In an inverting amplifier configuration, what is the phase difference between the input and output signals?

• 0 degrees

• 90 degrees

• 180 degrees

• 270 degrees

Answer explanation

In an inverting amplifier, the output signal is inverted relative to the input. This means there is a phase difference of 180 degrees between the input and output signals, making 180 degrees the correct choice.

Which of the following is the formula for the voltage gain of an inverting amplifier?

Answer explanation

The voltage gain of an inverting amplifier is given by the formula -Rf/Rin. This indicates that the output voltage is inverted and scaled by the ratio of the feedback resistor (Rf) to the input resistor (Rin).

In a non-inverting amplifier, if the input voltage is 2V and the gain is 5, what is the output voltage?

• 2V

• 5V

• 10V

• 15V

Answer explanation

In a non-inverting amplifier, the output voltage (Vout) is calculated using the formula Vout = Vin * Gain. Here, Vin = 2V and Gain = 5, so Vout = 2V * 5 = 10V. Therefore, the correct answer is 10V.

What is the gain-bandwidth product of an op-amp?

• The product of the gain and the bandwidth

• The sum of the gain and the bandwidth

• The difference between the gain and the bandwidth

• The ratio of the gain to the bandwidth

Answer explanation

The gain-bandwidth product of an op-amp is defined as the product of the gain and the bandwidth. This means that as the gain increases, the bandwidth decreases, keeping the product constant.

Which component is primarily responsible for providing feedback in an op-amp circuit?

• Capacitor

• Resistor

• Inductor

• Diode

Answer explanation

In an op-amp circuit, the resistor is primarily responsible for providing feedback. It sets the gain and stabilizes the output by controlling the amount of output voltage fed back to the inverting input.

What is the typical unit of measurement for the gain-bandwidth product?

• Hertz (Hz)

• Decibels (dB)

• Volts (V)

• Amperes (A)

Answer explanation

The gain-bandwidth product is typically measured in Hertz (Hz), as it represents the frequency range over which an amplifier can operate effectively. Other units like dB, V, and A are not suitable for this measurement.

In a feedback loop of an op-amp, what is the purpose of negative feedback?

• To increase the gain

• To stabilise the gain

• To decrease the bandwidth

• To increase the input impedance

Answer explanation

Negative feedback in an op-amp is used to stabilise the gain by reducing the effects of variations in the input signal and component tolerances, ensuring consistent performance.

Which of the following is a common application of operational amplifiers?

• Digital signal processing

• Audio amplification

• Data storage

• Wireless communication

Answer explanation

Operational amplifiers are widely used in audio amplification due to their ability to amplify weak audio signals, making 'Audio amplification' the correct choice. Other options like digital signal processing and data storage are less common applications.

What is the input impedance of an ideal op-amp?

• 0 ohms

• 50 ohms

• 1000 ohms

• Infinite

Answer explanation

An ideal op-amp has infinite input impedance, meaning it draws no current from the input source. This characteristic allows for minimal loading on the preceding circuit, making 'infinite' the correct choice.