Electronic Science - Online Test
Q1. Consider the set of strings on {0,1} in which, every substring of 3 symbols has at most two
zeros. For example, 001110 and 011001 are in the language, but 100010 is not. All strings of
length less than 3 are also in the language. A partially completed DFA that accepts this
language is shown below.
The missing arcs in the DFA are
Answer : Option D
Explaination / Solution:
The complete DFA is
Q2. 
In the figure shown below, the chopper feeds a resistive load from a battery source. MOSFET Q is switched at 250 kHz, with a duty ratio of 0.4. All elements of the circuit are assumed to be ideal
The average source current in Amps in steady-state is
Answer : Option B
Explaination / Solution:
No Explaination.
Q3. A 10 kHz even-symmetric square wave is passed through a bandpass filter with centre frequency at 30 kHz and 3 dB passband of 6 kHz. The filter output is
Answer : Option C
Explaination / Solution:
10 KHz even symmetric square wave have frequency component present 10KHz, 30KHz, 50KHz, 70KHz
[only odd harmonics due to half wave symmetry]
Since bandpass filter is contered at 30KHz, 30KHz component will pass through
filter output is nearly perfect cosine wave at 10 KHz
Cosine in due to reason that signal in even signal.
Q4. A 3-phase balanced load which has a power factor of 0.707 is connected to balanced supply. The power consumed by the load is 5kW. The power is measured by the two wattmeter method. The readings of the two wattmeters are
Answer : Option A
Explaination / Solution:
satisfiying only for(A)
Q5.
If R is the radius of a spherical conductor, the dielectric strength, maximum electric-field magnitude to which it can be raised is
Answer : Option A
Explaination / Solution:
Dielectric strength is the maximum electric field intensity the medium can bear without suffering a breakdown. The electric field intensity has a maximum value on the surface of the spherical conductor, therefore,
Q6. A single-phase, 22 kVA, 2200 V/ 220 V, 50 Hz, distribution transformer is to be connected as an auto-transformer to get an output voltage of 2420 V. Its maximum kVA rating as an autotransformer is
Answer : Option C
Explaination / Solution:
Q7. A silicon wafer has 100 nm of oxide on it and is furnace at a temperature above
10000 C for further oxidation in dry oxygen. The oxidation rate
Answer : Option D
Explaination / Solution:
No Explaination.
Q8. According to Ampere's circuital law
Answer : Option A
Explaination / Solution:
the expression for Ampere’s circuital law is where I is the current included in the surface bounded by the line integral.
Q9. The average power delivered to an impedance (4 - j3)Ω by a current 5cos(100πt +100) A is
Answer : Option B
Explaination / Solution:
Q10. Figure shows current in a part of an electrical circuit. Then current I is
Answer : Option A
Explaination / Solution:
Using Kirchhoff’s junction rule at junction A,2 + 5 - 2 - 1 + IAB = 0;IAB = - 4A
The current IAB is directed away from the junction A. Using the junction rule at B 4 + 0.2 - 1.7 - I = 0;
I = 2.5A
