Technical Officer, SCERT • 2025 • Paper-II
Transistor in power amplifier is
A)
A voltage generating device
B)
A op-amp
C)
A passive device
D)
An active device
Option D is correct: An active device.
Technical Officer, SCERT • 2025 • Paper-II
Maxwell second equation is based on which law?
A)
Coulomb law
B)
Lenz law
C)
Ampere law
D)
Faraday law
Option D is correct: Faraday law.
Technical Officer, SCERT • 2025 • Paper-II
Oscillators have feedback-
A)
Negative
B)
Positive
C)
Either Positive or negative
D)
No
Option B is correct: Positive.
Technical Officer, SCERT • 2025 • Paper-II
What will be the collector efficiency of a power amplifier having zero signal power dissipation of 5 watts and a.c. power output of 2 watts?
A)
70%
B)
90%
C)
40%
D)
30%
Option D is correct: 30%.
Technical Officer, SCERT • 2025 • Paper-I
Which of the following equation represents mass action law for semiconductors in electronic circuits?
A)
nxp=n^2
B)
nxp=ni^2
C)
nxp=n^4
D)
nxp=ni^4
Option B is correct: nxp=ni^2.
Technical Officer, SCERT • 2025 • Paper-I
What is the function of an inductor?
A)
Makes the change in current
B)
Oppose the change in current
C)
Allows the constant current
D)
Allows the change in current
Option B is correct: Oppose the change in current.
Technical Officer, SCERT • 2025 • Paper-I
Find x(0) if X(z) = 2z / (z-0.6).
A)
0.6
B)
0.36
C)
0
D)
2
Option D is correct: 2.
Technical Officer, SCERT • 2025 • Paper-I
Laplace transform changes the ___ domain function to the ___ domain function.
A)
time, time
B)
time, frequency
C)
frequency, time
D)
frequency, frequency
Option B is correct: time, frequency.
Technical Officer, SCERT • 2025 • Paper-I
The Z-transform of a discrete signal is given as X(z) = 2z^0 + z. The discrete signal is-
A)
causal
B)
anti-causal
C)
non-causal
D)
not enough information
Option B is correct: anti-causal.
Technical Officer, SCERT • 2025 • Paper-I
Avalanche photodiodes are preferred over PIN diodes in optical communication systems because of-
A)
speed of operation
B)
higher sensitivity
C)
larger bandwidth
D)
larger power handling capacity
Option B is correct: higher sensitivity.
Technical Officer, SCERT • 2025 • Paper-I
If a signal f(t) has energy E, the energy of the signal f(3t) is equal to
A)
E
B)
E/3
C)
Ef
D)
E/9
Option B is correct: E/3.
Technical Officer, SCERT • 2025 • Paper-I
A battery is connected across the series combination of two resistors of values 5 Ω and 30 Ω. The voltage across the 5 Ω resistor is 20 V. The battery voltage is-
A)
120V
B)
140V
C)
175 V
D)
200V
Option A is correct: 120V.
Technical Officer, SCERT • 2025 • Paper-I
A passive RC high pass filter is composed of a 20 Ω resistor and a 4 μF capacitor. The cut-off frequency of the filter is approximately-
A)
8KHz
B)
5 KHz
C)
3 KHz
D)
2KHz
Option D is correct: 2KHz.
Technical Officer, SCERT • 2025 • Paper-I
Tellegen’s Theorem is valid for ____ network.
A)
linear or non-linear
B)
passive or active
C)
time variant or time invariant
D)
all of the mentioned
Option D is correct: all of the mentioned.
Technical Officer, SCERT • 2025 • Paper-I
In a semiconductor, the energy gap between the valence band and conduction band is about
A)
5eV
B)
10eV
C)
15eV
D)
1eV
Option D is correct: 1eV.
Technical Officer, SCERT • 2025 • Paper-I
Which of the following transistors is affected by static electricity?
A)
UJT
B)
JFET
C)
MOSFET
D)
NPN transistor
Option C is correct: MOSFET.
Technical Officer, SCERT • 2025 • Paper-I
Thermal runaway in a transistor biased in the active region is due to
A)
heating of the transistor
B)
changes in Vbe which increases the temperature
C)
base-emitter voltage which decreases with rise in temperature
D)
change in reverse collector saturation current due to rise in temperature
Option D is correct: change in reverse collector saturation current due to rise in temperature.
Technical Officer, SCERT • 2025 • Paper-I
Two ports network containing sources in their branches are called-
A)
three port
B)
one port
C)
passive ports
D)
active ports
Option D is correct: active ports.
Technical Officer, SCERT • 2025 • Paper-I
In a forward biased photo diode, with increase in incident light intensity, the diode current
A)
Increases
B)
Remains constant
C)
Decreases
D)
Remaining constant, the voltage drop across diode increases
Option A is correct: Increases.
Technical Officer, SCERT • 2025 • Paper-I
The dual pair of resistance is-
A)
inductance
B)
capacitance
C)
conductance
D)
current
Option C is correct: conductance.
Technical Officer, SCERT • 2025 • Paper-I
In an integrated circuit, the SiO2 layer provides-
A)
electrical connection to external circuit
B)
physical strength
C)
isolation
D)
conducting path
Option C is correct: isolation.
Technical Officer, SCERT • 2025 • Paper-I
In which material the temperature coefficient is linear over a large range of temperature?
A)
Copper
B)
Tungsten
C)
Nickel
D)
Platinum
Option D is correct: Platinum.
Technical Officer, SCERT • 2025 • Paper-I
Find the Fourier transform of an exponential signal f(t) = e^{-at} u(t), a>0.
A)
1/(a+jω)
B)
1/(a-jω)
C)
a+jω
D)
a-jω
Option A is correct: 1/(a+jω).
Technical Officer, SCERT • 2025 • Paper-I
The Laplace transform of the signal sin 5t is
A)
5/(s^2 + 25)
B)
5/(s^2 + 4)
C)
5/(s^2 + 25)
D)
3/(s^2 + 3)
Option A is correct: 5/(s^2 + 25).
Technical Officer, SCERT • 2025 • Paper-I
The doping concentrations of an npn transistor are- X: 5x10^17 cm^-3, Y: 2x10^15 cm^-3, Z: 10^16 cm^-3. Identify the regions in the order X, Y, Z.
A)
Collector, Base, Emitter
B)
Emitter, Base, Collector
C)
Collector, Emitter, Base
D)
Emitter, Collector, Base
Option B is correct: Emitter, Base, Collector.
