Electrical Engineering - Online Test
Q1.
A communication channel with AWGN operating at a signal to noise ration SNR >> 1 and bandwidth B has capacity C1. If the SNR is doubled keeping constant, the resulting capacity C2 is given by
Answer : Option B
Explaination / Solution:
Q2. For a BJT the common base current gain α = 0.98 and the collector base
junction reverse bias saturation current ICO = 0.6 μA. This BJT is connected in
the common emitter mode and operated in the active region with a base drive
current IB = 204 A. The collector current IC for this mode of operation is
Answer : Option D
Explaination / Solution:
In active region, for common emitter amplifier,
Substituting ICO = 0.6 μA and IB = 204 μA in above eq we have,
IC = 1.01 mA
Q3. In a microprocessor, the service routine for a certain interrupt starts from a fixed location of memory which cannot be externally set, but the interrupt can be delayed or rejected Such an interrupt is
Answer : Option D
Explaination / Solution:
Vectored interrupts : Vectored interrupts are those interrupts in which program control transferred to a fixed memory location.
Maskable interrupts : Maskable interrupts are those interrupts which can be rejected or delayed by microprocessor if it is performing some critical task.
Q4. 
Answer : Option A
Explaination / Solution:
Q5. The Thevenin equivalent impedance Zth between the nodes P and Q in the
following circuit is
Answer : Option A
Explaination / Solution:
Killing all current source and voltage sources we have,
Q6. A discrete time linear shift - invariant system has an impulse response h[n] with h[0] = 1,h[1] =- 1,h[2] = 2, and zero otherwise The system is given an input sequence x[n] with x[0] = x[2] = 1, and zero otherwise. The number of nonzero samples in the output sequence y[n], and the value of y[2] are respectively
Answer : Option D
Explaination / Solution:
Q7. 
A transmission line terminates in two branches, each of length 
as shown. The branches are terminated by 50W loads. The lines are lossless and have the characteristic impedances shown. Determine the impedance Zi as seen by the source.
as shown. The branches are terminated by 50W loads. The lines are lossless and have the characteristic impedances shown. Determine the impedance Zi as seen by the source.
Answer : Option D
Explaination / Solution:
The transmission line are as shown below. Length of all line is 
Q8. The magnitude plot of a rational transfer function G(s) with real coefficients is shown below. Which of the following compensators has such a magnitude plot ?
Answer : Option C
Explaination / Solution:
This compensator is roughly equivalent to combining lead and lad compensators in the same design and it is referred also as PID compensator.
Q9. For the BJT QL in the circuit shown below, 
The
switch is initially closed. At time t = 0, the switch is opened. The time t at
which Q1 leaves the active region is
The
switch is initially closed. At time t = 0, the switch is opened. The time t at
which Q1 leaves the active region is
Answer : Option C
Explaination / Solution:
Applying KCL at collector
with time, the capacitor charges and voltage across collector changes from 0
towards negative.
Q10. 
For the 8085 assembly language program given below, the content of the accumulator after the execution of the program is
Answer : Option C
Explaination / Solution:
By executing instruction one by one
