Electrical Engineering - Online Test
Q1. Which one of the following is an eigen function of the class of all continuous-time, linear, time-invariant systems u(t) denotes the unit-step function)?
Answer : Option C
Explaination / Solution:
No Explaination.
Q2. Two magnetically uncoupled inductive coils have Q factors q1 and q2 at the
chosen operating frequency. Their respective resistances are R1 and R2. When
connected in series, their effective Q factor at the same operating frequency is
Answer : Option C
Explaination / Solution:
The quality factor of the inductances are given by
So, in series circuit, the effective quality factor is given by
Q3. A plant transfer function is given as 
When the plant operates in a unity feedback configuration, the condition for the stability of the closed loop system is
When the plant operates in a unity feedback configuration, the condition for the stability of the closed loop system is
Answer : Option A
Explaination / Solution:
Given plant transfer function,
So, closed loop transfer function is
Therefore, characteristics equation is
For stability, we form the Routh array.
For stability, we must have
Q4. The order of the differential equation
Answer : Option B
Explaination / Solution:
The highest derivative terms present in DE is of 2nd order.
Q5.
Consider a delta connection of resistors and its equivalent star connection as shown below. If all elements of the delta connection are scaled by a factor k, k > 0, the elements of the corresponding star equivalent will be scaled by a factor of
Answer : Option B
Explaination / Solution:
In the equivalent star connection, the resistance can be given as
Q6. The output Y in the circuit below is always ‘1’ when
Answer : Option B
Explaination / Solution:
The given circuit is shown below:
If any two or more inputs are ‘1’ then output y will be 1.
Q7. A continuous-time function x(t) is periodic with period T. The function is sampled uniformly
with a sampling period TS. In which one of the following cases is the sampled signal periodic?
Answer : Option B
Explaination / Solution:
Q8. 
The pole-zero diagram of a causal and stable discrete-time system is shown in the figure. The zero at the origin has multiplicity 4. The impulse response of the system is h[n]. If h[0] = 1, we can conclude
Answer : Option A
Explaination / Solution:
From the pole-zero plot, we obtain the transfer function as
Q9. The circuit shown below is driven by a sinusoidal input Vi = Vpcos(t/RC). The
steady state output vo
Answer : Option A
Explaination / Solution:
parallel combination of R and C equivalent impedance is
Transfer function can be written as
Q10. The eigen values of a skew-symmetric matrix are
Answer : Option C
Explaination / Solution:
Eigen value of a Skew-symmetric matrix are either zero or pure imaginary in conjugate pairs.
