Electrical Engineering - Online Test
Q1. The circuit shown in the figure is used to charge the capacitor C alternately
from two current sources as indicated. The switches S1 and S2 are mechanically
coupled and connected as follows:
Assume that the capacitor has zero initial charge. Given that u(t) is a unit step function , the voltage vc(t) across the capacitor is given by
Answer : Option C
Explaination / Solution:
Q2. For the power semiconductor devices IGBT, MOSFET, Diode and Thyristor, which one of the following statements is TRUE?
Answer : Option D
Explaination / Solution:
MOSFET → Majority carrier device (NMOS, PMOS)
Diode → both majority & minority carrier device
Transister → Npn, pnp
IGBT → input is MOSFET, Output is BJT
Q3. Silicon is doped with boron to a concentration of 4 × 1017 atoms cm3. Assume
the intrinsic carrier concentration of silicon to be 1.5 × 1010/cm3 and the value
of kT/q to be 25 mV at 300 K. Compared to undopped silicon, the fermi level
of doped silicon
Answer : Option C
Explaination / Solution:
Q4. A uniform plane wave in the free space is normally incident on an infinitely thick dielectric slab (dielectric constant ε = 9). The magnitude of the reflection coefficient is
Answer : Option C
Explaination / Solution:
Q5. 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:
No Explaination.
Q6. The pressure coil of a dynamometer type wattmeter is
Answer : Option B
Explaination / Solution:
Since all the applied voltage appears across it.
Q7. All the values of the multi-valued complex function
1i, where 
Answer : Option B
Explaination / Solution:
Q8. Consider an LTI system with transfer function
If the input to the system is cos(3t) and the steady state output is Asin (3t + α), then the value of A is
Answer : Option B
Explaination / Solution:
Q9. A discrete system is represented by the difference equation
It has initial condition X1(0) = 1; X2(0) = 0. The pole location of the system for a = 1, are
Answer : Option A
Explaination / Solution:
from the given difference equation,
Q10. A 20-pole alternators is having 180 identical stator slots with 6 conductors in
each slot. All the coils of a phase are in series. If the coils are connected to realize
single-phase winding, the generated voltage is V1. If the coils are reconnected to
realize three phase star connected winding, the generated phase voltage is V2.
Assuming full pitch, single-layer winding, the ratio V1/V2is
Answer : Option D
Explaination / Solution:
