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Past Questions — 2026
Huffman coding is an example of:
A)
Lossless compression
B)
Lossy compression
C)
Error correction
D)
Modulation
Correct option A: Lossless compression
Power measurement at microwave frequencies uses:
A)
Bolometer
B)
Multimeter
C)
Oscilloscope
D)
Spectrum analyzer
Correct option A: Bolometer
Channel capacity increases with:
A)
Higher SNR
B)
Lower bandwidth
C)
Higher redundancy
D)
Lower entropy
Correct option A: Higher SNR
Which of the following devices cannot be used as a microwave oscillator?
A)
IMPATT diode
B)
TRAPATT diode
C)
PN Junction diode
D)
BARITT diode
Microwave oscillators are typically made using negative-resistance devices such as IMPATT, TRAPATT, and BARITT diodes. These devices can generate high-frequency microwave signals. A normal PN junction diode does not exhibit the required negative resistance or avalanche/transit-time behavior needed for microwave oscillation, so it cannot be used as a microwave oscillator.
Magnetron is commonly used in:
A)
Radar systems
B)
Satellite communication
C)
Audio amplifiers
D)
Optical fiber
A magnetron is a high-power microwave oscillator. Its most common application is in radar systems, where it generates the microwave energy needed for transmitting pulses. It is not used for satellite communication (which typically uses klystrons, TWTs, or solid-state amplifiers), nor for audio amplifiers or optical fiber systems.
What is the difference between computer architecture and computer organization?
A memory system has a total of 8 memory chips, each with 12 address lines and 4 data lines. The total size of the memory system is
A)
16 kbytes
B)
32 kbytes
C)
48 kbytes
D)
64 k bytes
Correct option A: 16 kbytes
I/O devices are connected to CPU through 16-bit
A)
Registers
B)
Buses
C)
ALU
D)
Control unit
Correct option B: Buses
In Pascal, begin and end are used to:
A)
Declare variables
B)
Mark program blocks
C)
Define loops
D)
End program
In Pascal, `begin` and `end` are block delimiters used to group multiple statements into a single program block. This is common in procedures, functions, loops, and conditional statements. They do not declare variables, define loops by themselves, or only end the entire program.
Antenna aperture efficiency is given by:
A)
Dλ / 4π
B)
Dλ^2 / 4π
C)
Dλ^2 / 4πA
D)
Dλ / 4πA
Antenna aperture efficiency is the ratio of the effective aperture to the physical aperture area. Using the relation between directivity and effective aperture, A_e = Dλ^2 / 4π, we get aperture efficiency = A_e / A = Dλ^2 / 4πA. Hence option (c) is correct. Option (a) and (d) have incorrect dimensions, and option (b) misses the division by the physical area A.
The octal equivalent of 100101_2 is:
A)
54
B)
45
C)
37
D)
25
Convert binary 100101 to octal by grouping bits in threes from the right: 100 101. These groups are 4 and 5 in octal, so the octal equivalent is 45. Hence, option (b) is correct. The other options do not match this grouping result.
The breakaway points of root loci are:
A)
Open loop poles
B)
Closed loop poles
C)
Open loop zeros
D)
Closed loop zeros
Breakaway points on a root locus are points on the real axis where two or more branches of the locus leave the real axis (or enter it). These points occur on segments between open-loop poles and zeros, and in standard root-locus theory they are associated with the open-loop pole locations/segments rather than closed-loop poles or zeros. Hence, the correct choice is open loop poles. Closed-loop poles are the moving points on the locus, while open-loop zeros are end points of some branches, not breakaway points.
A register is used to:
A)
Store multiple bits of data
B)
Generate clock signals
C)
Perform arithmetic operations
D)
Convert analog signals
A register in digital electronics is a small group of flip-flops used to store binary information temporarily. Since each flip-flop stores 1 bit, a register can store multiple bits of data. It does not generate clock signals, perform arithmetic operations, or convert analog signals.
Which circuit is used to generate square and triangular waveforms?
A)
Multivibrator
B)
Rectifier
C)
Amplifier
D)
Regulator
A multivibrator circuit is used to generate non-sinusoidal waveforms such as square and triangular waves. It can operate as an astable oscillator, producing continuous switching between two states. Rectifiers convert AC to DC, amplifiers increase signal amplitude, and regulators maintain a constant voltage, so they are not used for waveform generation.
Which of these flip – flops cannot be used to construct a serial shift register?
A)
D – flip flop
B)
SR flip – flop
C)
T flip – flop
D)
JK flip – flop
A serial shift register is commonly built using flip-flops that can directly transfer the input data from one stage to the next in a controlled way. D flip-flops, T flip-flops, and JK flip-flops can be arranged to form shift registers. However, the SR flip-flop has the invalid condition when both S and R are 1, which makes it unsuitable for reliable shift-register construction. Therefore, SR flip-flop cannot be used to construct a serial shift register.
Which of the following memories uses one transistor and one capacitor as basic memory unit:
A)
SRAM
B)
DRAM
C)
Both SRAM and DRAM
D)
None of these
DRAM (Dynamic RAM) stores each bit using one transistor and one capacitor. The capacitor holds the charge representing the bit, and the transistor acts as the access switch. In contrast, SRAM uses a flip-flop made of multiple transistors, not a single transistor-capacitor pair. Therefore, the correct answer is DRAM.
State and explain the basic laws and theorems of Boolean algebra. Simplify a given Boolean expression using these laws.
Explain the construction and significance of the Nyquist Stability Criterion for determining the stability of closed-loop systems.
Describe the operation of rectifiers and power supplies. Explain the role of filters in improving the output of a rectifier circuit.
Which flip-flop has no invalid state?
A)
RS flip-flop
B)
JK flip-flop
C)
D flip-flop
D)
T flip-flop
The JK flip-flop has no invalid or forbidden state. In an RS flip-flop, the S=R=1 condition is invalid because it leads to an undefined output. The JK flip-flop removes this problem by using feedback, so when J=K=1, the output toggles instead of becoming invalid. D and T flip-flops are also free from invalid states, but in standard exam questions asking for the flip-flop with no invalid state among these, the JK flip-flop is the intended answer because it is the improved form of RS flip-flop with the forbidden condition eliminated.
Poynting vector gives the:
A)
rate of energy flow
B)
intensity of electric field
C)
intensity of magnetic field
D)
direction of polarization
The Poynting vector represents the rate at which electromagnetic energy flows per unit area, i.e., the energy flux of an electromagnetic wave. Its direction gives the direction of energy propagation. Therefore, the correct answer is (a). Options (b) and (c) are incorrect because electric and magnetic field intensities are described by E and B/H fields, not the Poynting vector. Option (d) is also incorrect because polarization refers to the orientation of the electric field, not energy flow.
If a system is critically damped and the gain is increased, the system:
A)
becomes overdamped
B)
becomes underdamped
C)
becomes oscillatory
D)
remains critically damped
For a second-order control system, critical damping occurs at the boundary between overdamped and underdamped behavior. If the gain is increased, the damping ratio effectively decreases, so the system moves past the critical point into the underdamped region. An underdamped system exhibits oscillatory response. Hence, the correct answer is (c).
Pulse shaping circuits are mainly used in:
A)
Communication systems
B)
Power transmission
C)
Rectification
D)
Voltage regulation
Pulse shaping circuits are used to modify the shape of electrical pulses so they suit transmission and processing requirements. This is mainly important in communication systems, where pulses must have suitable rise time, width, and spectral characteristics. They are not primarily used for power transmission, rectification, or voltage regulation, which are handled by different circuit types.
The Opamp comparator circuit uses
A)
positive feedback
B)
negative feedback
C)
regenerative feedback
D)
no feedback
An op-amp used as a comparator operates in open-loop mode, meaning there is no feedback path from output to input. Because of the very high open-loop gain, even a tiny difference between the input voltages drives the output into saturation. Positive feedback is used in Schmitt trigger circuits, negative feedback is used in linear amplifier applications, and regenerative feedback is not the standard comparator configuration.
Which of the following options correctly represent the characteristic of Excess – 3 code?
A)
It is a reflexive as well as a sequential code
B)
It is a reflexive code but not a sequential code
C)
It is a sequential code but not a reflexive code
D)
It is neither a reflexive code nor a sequential code
Excess-3 (XS-3) code is a non-weighted decimal code obtained by adding 3 to each decimal digit and then converting to binary. It is neither reflexive (self-complementing) in the sense of directly mirroring natural binary order, nor sequential, because the code words do not follow the normal binary counting sequence. Hence, the correct choice is (d).