Tag: physics

Quizzes (598) Questions (13441)

Questions Related to physics

Multiple choice relativistic mechanics option a: relativity physics

According to special theory of relativity which one is not an absolute quantity?

  1. time

  2. mass

  3. height

  4. both a and b
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
According to classical physics time and mass are not an absolute quantity
Multiple choice properties of an ideal op-amp electronics physics the operational amplifier (op-amp)

The supply voltage to an opamp is +-15volts. The opamp is connected as an inverting amplifier of gain -20. The output voltage for an input voltage of 20mV is:

  1. -400 mV
    • 400 mV

  3. -200 mV

  4. +200 mV
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Voltage gain and output voltage are related by the formula $A _v=\dfrac{output \ voltage}{input \ voltage}$. Substituting the value of input voltage, we get, output voltage = - 20 x 20mV = -400 mV

Multiple choice properties of an ideal op-amp electronics physics the operational amplifier (op-amp)

The advantage of having an infinite bandwidth in an Ideal op amp is

  1. Signals can be amplified without attenuation

  2. Output common-mode noise voltage is zero

  3. Output voltage occurs simultaneously with input voltage changes

  4. Output can drive infinite number of device
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

 An ideal op-amp has infinite bandwidth. Therefore, any frequency signal from 0 to $\infty$ Hz can be amplified without attenuation.

Multiple choice properties of an ideal op-amp electronics physics the operational amplifier (op-amp)

An ideal Opamp is an ideal

  1. Current controlled current source

  2. current controlled voltage source

  3. Voltage controlled voltage source

  4. Voltage controlled current source
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The ideal opamp voltage is maintained constant. It is controlled by the input voltage. Thus the output of an opamp is controlled by the source (input) voltage

Multiple choice properties of an ideal op-amp electronics physics the operational amplifier (op-amp)

The slew rate of an ideal opamp is

  1. Infinite

  2. Zero

  3. Half of the voltage gain

  4. 10 times the voltage gain
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

In an ideal opamp, output follows the input instantly and hence the time delay is zero. slew rate is calculated as the ratio of change in voltage at the output to time taken for this action to take place. If time delay is zero, the slew rate will be infinite

Multiple choice properties of an ideal op-amp electronics physics the operational amplifier (op-amp)

An opamp has a supply voltage of 9V AND -9V at its power terminals. What is the maximum output voltage one can obtain by varying the voltage across the inverting and non inverting terminals 

  1. Greater than 9V

  2. 9V

  3. 18V

  4. Can be infinity depending on the voltage gain of the opamp
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

maximum voltage that can obtained will be equal to the supply voltage w.r.t ground and beyond which the amplifier will saturate

Multiple choice properties of an ideal op-amp electronics physics the operational amplifier (op-amp)

An AC signal with frequencies 1000 Hz, 1500 Hz and 2500 Hz are fed to the inverting terminal of an opamp. The voltage level of all these signals are 2V. If 1000 Hz signal is amplified by 20 times, then

  1. 2500 Hz signal will get amplified by 50 times

  2. 2500 Hz signal will get amplified by 20 times

  3. 1500 Hz signal will get amplified by 15 times

  4. 2500 Hz signal will get amplified by 10 times
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

In an ideal op-amp circuit, the gain is independent of the frequency of the input signal within the bandwidth. If the 1000 Hz signal is amplified by 20 times, other signals within the bandwidth will also be amplified by the same factor.

Multiple choice properties of an ideal op-amp electronics physics the operational amplifier (op-amp)

The ideal opamp has the following characteristics

  1. Input resistance = Infinity; Voltage gain = Infinity

  2. Input resistance = zero; Voltage gain = Infinity

  3. Input resistance = zero; Voltage gain = zero

  4. Input resistance = Infinity; Voltage gain = zero
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The ideal op-amp has infinite high input resistance and infinite voltage gain.

The ideal op-amp will have infinite voltage gain.Op-amp are devices that many times are used to function as amplifiers. A voltage is input into the op-amp and as output, it produces the voltage amplified.
An ideal op-amp will have infinite high input resistance.This will ensure that the op-amp causes no loading in the circuit.

Multiple choice properties of an ideal op-amp electronics physics the operational amplifier (op-amp)

The open loop voltage gain in an opamp 

  1. reduces if voltage across the inverting and non inverting terminal are same

  2. reduces if voltage across the inverting terminal is zero

  3. increases if voltage across the inverting and non inverting terminal are same

  4. remains the same, if voltage across any of these terminals are changed
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Open loop voltage gain is given by $A _v=\dfrac{V _0}{V _+-V _-}$. If $V _+=V _-$, Voltage gain becomes infinity or very high. thus voltage gain increases