Electronics Engineering - Online Test
Q1.
The ratio of the mobility to the diffusion coefficient in a semiconductor has the units
Answer : Option A
Explaination / Solution:
Q2. The increasing order of speed of data access for the following devices is
i. Cache Memory
ii. CDROM
iii. Dynamic RAM
iv. Processor Registers
v. Magnetic Tape
Answer : Option B
Explaination / Solution:
No Explaination.
Q3. The electron and hole concentrations in an intrinsic semiconductor are ni per cm3 at 300 K. Now, if acceptor impurities are introduced with a concentration
of NA per cm3
(where NA >> ni , the electron concentration per cm3 at 300 K
will be
Answer : Option D
Explaination / Solution:
As per mass action law
np = ni
If acceptor impurities are introduces
Q4. In the given network V1 = 100∠0° V, V2 = 100∠ − 120° V, V3 = 100∠ + 120° V. The phasor
current 𝑖 (in Ampere) is
Answer : Option D
Explaination / Solution:
Q5. In the given network V1 = 100∠0°V, V2 = 100∠-120°V, V3 = 100∠+120°V. The phasor
current i (in Ampere) is
Answer : Option A
Explaination / Solution:
Q6. In the circuit shown, the op-amp has finite input impedance, infinite voltage
gain and zero input offset voltage. The output voltage Vout is
Answer : Option C
Explaination / Solution:
Given that the op-amp has infinite voltage gain, i.e.
AOL =
and zero input offset voltage
VIO = 0
So, we redraw the op-amp circuit as
Hence, the current I1 is drawn through resistance R2. So, the output voltage is
Vout = I1R2
Q7. The open loop transfer function of a unity feedback control system is given by
The closed loop system will be stable if,
Answer : Option C
Explaination / Solution:
Q8. Let z(t) = x(t) * y(t), where "*" denotes convolution. Let C be a positive real-valued constant. Choose the correct expression for z (ct).
Answer : Option A
Explaination / Solution:
Q9. Consider the following statements regarding the complex Poynting vector 
for
the power radiated by a point source in an infinite homogeneous and lossless
medium. Re(
) denotes the real part of 
denotes a spherical surface whose
centre is at the point source, and 
denotes the unit surface normal on S.
Which of the following statements is TRUE?
for
the power radiated by a point source in an infinite homogeneous and lossless
medium. Re() denotes the real part of denotes a spherical surface whose
centre is at the point source, and denotes the unit surface normal on S.
Which of the following statements is TRUE?
Answer : Option C
Explaination / Solution:
Power radiated from any source is constant.
Q10. A speed signal, band limited to 4 kHz and peak voltage varying between +5 V and -5 V, is sampled at the Nyquist rate. Each sample is quantized and represented by 8 bits.
If the bits 0 and 1 are transmitted using bipolar pulses, the minimum bandwidth required for distortion free transmission is
Answer : Option B
Explaination / Solution:
