Tag: electronics

Quizzes (5) Questions (36)

Questions Related to electronics

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

In a differential connection, the signals that are opposite at the inputs are _____ amplified, and those that are common to the two inputs are _____ amplified.

  1. slightly, slightly

  2. slightly, highly

  3. highly, highly

  4. highly, slightly
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Differential amplifiers are designed to amplify the difference between two signals (highly amplified) while rejecting signals common to both inputs, such as noise (common-mode rejection, slightly amplified).

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

Current cannot flow to ground through

  1. A mechanical ground

  2. An ac ground

  3. A virtual ground

  4. An ordinary ground
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
  1. Virtual ground refers to a circuit elements that is not connected to the ground directly, it is held at a reference voltage. This reference voltage need not to be same voltage as ground either.
    2. While in all other ground it may be mechanical A.C or an ordinary ground it act as a reference point against which other voltage can be measured.
    3. The key point  is that the current flow from one point of the circuit through ground then back into the circuit.
    So, current cannot flow to ground through a virtual ground.
Multiple choice properties of an ideal op-amp electronics physics the operational amplifier (op-amp)

Why are the Op-amps with open loop configuration not used in linear applications?

  1. High risk of distortion

  2. High risk of clipping of output signal

  3. Both a & b

  4. works as an attenuator
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Open loop configuration of Op-amp may increase the threat of distortion as well as clipping of output signal. Due to this reason, the output gets switched between the positive and negative saturation levels.

Hence, this is the major drawback because of which it is highly impossible to use Op-amps with open loop configurations in linear circuit applications.

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

 A certain inverting amplifier has a closed-loop voltage gain of 25. The Op-amp has an open-loop voltage gain of 100,000. If an Op-amp with an open-loop voltage gain of 200,000 is substituted in the arrangement, the closed-loop gain ..

  1. doubles

  2. drops to 12.5

  3. remains at 25

  4. increases slightly
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

the closed loop gain is given by $A _{cl}=\dfrac{A}{1+A \beta}$. since the open loop gain is large, the closed loop gain almost remains a constant, as it will be independent of open loop gain 

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

Since the input impedance of an ideal operational amplifier is infinite.

  1. Its input current is zero

  2. Its output resistance is high

  3. Its output voltage becomes independent of load resistance

  4. It becomes a current controlled device
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Input current in an ideal operational amplifier   $i = \dfrac{V}{Z}$
Since,  input impedance of the ideal operational amplifier is infinite  $i.e. Z = \infty$
$\implies \ i =\dfrac{V}{\infty}= 0$