Electronic Science - Online Test
Q1. A single-phase full-bridge voltage source inverter (VSI) is fed from a 300 V battery. A pulse of 120º duration is used to trigger the appropriate devices in each half-cycle. The rms value of the fundamental component of the output voltage, in volts, is
Answer : Option A
Explaination / Solution:
Q2. Two identical NMOS transistors M1 and M2 are connected as shown below.
Vbias is chosen so that both transistors are in saturation. The equivalent gm of
the pair is defied to be 
at constant Vout 
at constant Vout The equivalent gm of the pair is
Answer : Option C
Explaination / Solution:
No Explaination.
Q3. magnitude of the magnetic moment of an electron of mass me if e is the charge on the electron and angular momentum is l, is
Answer : Option A
Explaination / Solution:
The electron moving in a circular orbit of radius r with a speed v and time period T constitutes a current .since,thereforeThe orbital magnetic moment of the electron The angular momentum of the electron ,sincetherefore,
Q4. If the length of the filament of a heater is reduced by 10% the power of the heater will
Answer : Option B
Explaination / Solution:
The power is related to resistance as,
So Power increases by 11%.
Q5. For paramagnetic materials
Answer : Option B
Explaination / Solution:
No Explaination.
Q6. In a semiconductor, the forbidden energy gap between the valance band and the conduction band is of the order of
Answer : Option B
Explaination / Solution:
The material which has electrical conductivity between that of a conductor and an insulator is called as semiconductor. Silicon, germanium and graphite are some examples of semiconductors.
In semiconductors, the forbidden gap between valence band and conduction band is very small. It has a forbidden gap of about 1 electron volt (eV).
Q7. Thyristor T in the figure below is initially off and is triggered with a single pulse of
width 10µs . It is given that 
Assuming latching
and holding currents of the thyristor are both zero and the initial charge on C is
zero, T conducts for
Assuming latching
and holding currents of the thyristor are both zero and the initial charge on C is
zero, T conducts for
Answer : Option C
Explaination / Solution:
No Explaination.
Q8. The Maxwell’s bridge shown in the figure is at balance. The parameters of the inductive coil are
Answer : Option A
Explaination / Solution:
No Explaination.
Q9. Correct formula for capacitance in terms of area A and distance d,of a parallel plate capacitor in vacuum is
Answer : Option D
Explaination / Solution:
The capacitance of a parallel plate capacitor is given by
Q10. The current state QAQB of a two JK flip-flop system is 00. Assume that the clock rise-time is much
smaller than the delay of the JK flip-flop. The next state of the system is
Answer : Option C
Explaination / Solution:
