Electronic Science - Online Test
Q1. 
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:
No Explaination.
Q2. An ammeter has a current range of 0-5A, and its internal resistance is 0.2Ω. In order to change
the range to 0-25A, we need to add a resistance of
Answer : Option D
Explaination / Solution:
No Explaination.
Q3. In a p-n junction, as the diffusion process continues the width of the depletion zone
Answer : Option D
Explaination / Solution:
No Explaination.
Q4. When a bipolar junction transistor is operating in the saturation mode, which one of the following statement is TRUE about the state of its collector-base (CB) and the baseemitter (BE) junctions?
Answer : Option C
Explaination / Solution:
No Explaination.
Q5. A Boolean function f(A,B,C,D) = ∏(1,5,12,15) is to be implemented using an 8×1
multiplexer (A is MSB). The inputs ABC are connected to the select inputs S2S1S0 of the
multiplexer respectively. 
Which one of the following options gives the correct inputs to pins 0,1,2,3,4,5,6,7 in order?
Answer : Option B
Explaination / Solution:
Q6. Consider the following combinational function block involving four Boolean variables x, y, a,
b where x, a, b are inputs and y is the output.
f (x, y, a, b)
{
if (x is 1) y = a;
else y = b;
}
Which one of the following digital logic blocks is the most suitable for implementing this
function?
Answer : Option C
Explaination / Solution:
‘x’ is working as selection line, where the two input lines are ‘a’ and
‘b’, so the function F (x, y,a,b) can be implemented using (2× 1)
multiplexer as follows:
Q7. Electrostatic shielding is based
Answer : Option B
Explaination / Solution:
Electric field inside a cavity is always zero. The potential inside a cavity of a conductor is constant. The potential difference between any two points inside a charged conductor is zero. This phenomenon is called electrostatic shielding.
Q8. Consider the Op-Amp circuit shown in the figure. 
The transfer function V(s) Vi(s)
Answer : Option A
Explaination / Solution:
Q9. A single-phase thyristor-bridge rectifier is fed from a 230 V, 50 Hz, single-phase AC mains. If it is delivering a constant DC current of 10 A, at firing angle of 30º, then value of the power factor at AC mains is
Answer : Option C
Explaination / Solution:
Q10. 
The OPAMP circuit shown above represents a
Answer : Option B
Explaination / Solution:
and from this equation it may be easily seen that this is the standard form of
T.F. of low pass filter
and form this equation it may be easily seen that this is the standard form of
T.F. of low pass filter
