# MCQs on Electric Circuits

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01․ Which of the following Y-parameters is dimensionless?
Y11.
none of these.
Y12.
Y22.

All the Y parameters are the ratio of current to voltage and therefore have unit mho.

02․ For finding the Z11 parameter at the input port of a two port network
output port is open circuited.
input port is open circuited.
input port is short circuited.
output port is short circuited.

Z11 = V1/I1 when I2 = 0. To make I2 = 0, the output port is to be open circuited.

03․ Unit step function is first derivative of
impulse function.
ramp function.
gate function.
parabolic function.

Ramp function is f(t) = t and unit step function is f(t) = 1. So the first derivative of ramp is a unit step.

04․ Which of the following is the correct relation?
AB-CD = 1 .
AC-BD = 1.
all of these.

AD-BC is the condition for reciprocity in case of ABCD parameters.

05․ Laplace transform analysis gives
frequency domain response only.
time domain response only.
both (a) and (b).
real response only.

Laplace transform transforms a function of time to a function of frequency.

06․ If a function is shifted by 'T', then it is correctly represented as
f (t-T) u (t).
f (t-T) u (t-T).
f (t) u (t).
f (t) u (t-T).

If a function is displaced by time T, then it is given as the product of the time displaced function and a unit step function displaced by same time T.

07․ The value of unity impulse function at time (t) = 0 is
0.
1.
infinite.
indeterminate.

Since the function is unit impulse, it will be 1 at time t = 0 and will be equal to 0 for any other time.

08․ The Laplace Transform of a shifted unit step f (t) = U (t-a) is
(e-as)/s.
e-as.
se-as.
s(1-e-as).

The laplace transform of a function displaced by time T is given by e-sT .F(s). F(s) is the laplace transform of the original signal.

09․ Which of the following theorems can be applied to any network- linear or nonlinear, active or passive, time variant or time invariant?
Thevnin theorem.
Tellegen theorem.
Norton Theorem.
Millman theorem.

Tellegen theorem is applicable to a very general class of lumped networks composed of elements that are - linear or nonlinear, active or passive, time variant or time invariant.

10․ Millman theorem yields equivalent
impedance.
both ‘c’ and ‘d’ .
voltage source.
current source.

Millman theorem gives the equivalent value of voltage or current for a network consisting of any number of current sources.

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