Electronics Engineering - Online Test
Q1. A bar of Gallium Arsenide (GaAs) is doped with Silicon such that the Silicon atoms occupy Gallium and Arsenic sites in the GaAs crystal. Which one of the following statement is true?
Answer : Option A
Explaination / Solution:
Silicon atoms act as P- type dopants in Arsenic sites and n- type dopants in Gallium sites.
Q2. The correct full wave rectifier circuit is
Answer : Option C
Explaination / Solution:
Q3. RA and RB are the input resistances of circuits as shown below. The circuits extend infinitely in the
direction shown. Which one of the following statements is TRUE?
Answer : Option D
Explaination / Solution:
Q4. The gain at the breakaway point of the root locus of a unity feedback system with open loop
transfer function 
is
is
Answer : Option A
Explaination / Solution:
Q5. 
Let a causal LTI system be characterized by the following differential equation, with initial rest condition
Where x(t) and y(t) are the input and output respectively. The impulse response of the system is (u(t) is the unit step function)
Answer : Option B
Explaination / Solution:
Q6. 
In the following network, the switch is closed at t = 0- and the sampling starts from t = 0. The sampling frequency is 10 Hz.
The samples x(n), n = (0, 1, 2, ...) are given by
Answer : Option B
Explaination / Solution:
No Explaination.
Q7. The circuit below implements a filter between the input current ii and the
output voltage v0. Assume that the opamp is ideal. The filter implemented is a
Answer : Option D
Explaination / Solution:
From diagram we can write 
Transfer function
Q8. A current sheet 
lies on the dielectric interface x = 0
between two dielectric media with εr1 = 5, μr1 = 1 in Region -1 (x < 0) and εr2 = 5, μr2 = 2 in Region -2(x > 0) . If the magnetic field in Region-1 at
x = 0- is 
the magnetic field in Region-2 at x = 0+ is
lies on the dielectric interface x = 0
between two dielectric media with εr1 = 5, μr1 = 1 in Region -1 (x < 0) and εr2 = 5, μr2 = 2 in Region -2(x > 0) . If the magnetic field in Region-1 at
x = 0- is the magnetic field in Region-2 at x = 0+ is
Answer : Option A
Explaination / Solution:
From boundary condition
Then from Boundary condition
Comparing we get A = 30 and B =- 10
Q9. For a narrow base PNP BJT, the excess minority carrier concentration (ΔnE for emitter, ΔpB for base. ΔnC for collector) normalized to equilibrium minority carrier concentration (nE0 for emitter, pB0 for base, nC0 for collector) in the quasi-neutral emitter, base and collector regions are shown below. Which one of the following biasing modes is the transistor operating in?
Answer : Option C
Explaination / Solution:
As per the change carrier profile, base – to – emitter junction is reverse bias and base to collector junction is forward bias, so it works in Inverse active.
Q10. X = and Y = are two 5-bit binary numbers represented in two’s complement format. The sum of X and Y represented in two’s complement format using 6 bits is
Answer : Option C
Explaination / Solution:
MSB of Y is 1, thus it is negative number and X is positive number
In signed two’s complements from 7 is
