Electronic Science - Online Test
Q1. 
A two-port network shown below is excited by external DC source. The voltage and the current are measured with voltmeters V1,V2 and ammeters. A1,A2 (all assumed to be ideal), as indicated
Under following conditions, the readings obtained are:
The h-parameter matrix for this network is
Answer : Option A
Explaination / Solution:
From the problem statement we have
Q2. 
The ac output voltage Vac is
Answer : Option B
Explaination / Solution:
The forward resistance of each diode is
Q3. The following FIVE instructions were executed on an 8085 microprocessor.
MVI A, 33H
MVI B, 78H
ADD B
CMA
ANI 32H
The Accumulator value immediately after the execution of the fifth instruction is
Answer : Option B
Explaination / Solution:
MVI A, 33H A⟵33H
MVI B, 78H B⟵78H
ADD B B⟵ABH
CMA A⟵54H
ANI 32H A⟵10H
A⟶0011 0011 A⟶1010 1011 0101 0100
B⟶0111 1000 B⟶0101 0100 0011 0010
1010 1011 0001 0000
Q4. The capacitance of a parallel plate capacitor is 5 μF. When a glass slab of thickness equal to the separation between the plates is introduced between the plates, the potential difference reduces to 1/8 of the original value. The dielectric constant of glass is
Answer : Option A
Explaination / Solution:
When a dielectric of constant K is introduced between the plates of a capacitor, the potential V reduces to V/K. Therefore K=8
Q5. 
In the following transistor circuit, 
, and 𝛽 and all the capacitances are very large
, and 𝛽 and all the capacitances are very largeThe value of DC current IE is
Answer : Option A
Explaination / Solution:
For the given DC values the Thevenin equivalent circuit is as follows
Q6. A small percentage of impurity is added to an intrinsic semiconductor at 300 K. Which one of
the following statements is true for the energy band diagram shown in the following figure?
Answer : Option A
Explaination / Solution:
New energy level is near to conduction band, so it is pentavalent atoms to form n-type semiconductor.
Q7.
Which one of the following gives the simplified sum of products expression for the Boolean function F =
m0 + m2 + m3 + m5, where m0,
m2, m3
and m5 are minterms corresponding to the inputs A, B and C with A as the MSB and C as the LSB?
and m5 are minterms corresponding to the inputs A, B and C with A as the MSB and C as the LSB?
Answer : Option B
Explaination / Solution:
F =
m0 + m2 + m3 + m5, ⟶ minterm
Q8. In an 8085 microprocessor, the shift registers which store the result of an addition and the overflow bit are, respectively
Answer : Option B
Explaination / Solution:
The shift registers A and F store the result of an addition and the overflow bit.
Q9. The dielectric constant K of an insulator can be
Answer : Option D
Explaination / Solution:
Dielectric constant of air is 1. All dielectrics generally have a value of the dielectric constant greater than1.where Fm is the force between two charged particles in a medium of dielectric constant K and F is the force between the two charges when placed in air.The force between two charges is greatest in air or vacuum and it decreases when any medium is placed between the charges. K cannot have negative, fractional or zero values.
Q10. 
For the two-port network shown below, the short-circuit admittance parameter matrix is
Answer : Option A
Explaination / Solution:
Given circuit is as shown below
By writing node equation at input port
By writing node equation at output port
From (1) and (2), we have admittance matrix
