Major Competitive Exams
Q. In a communication system, if the signal-to-noise ratio (SNR) is 20 dB, what is the linear SNR?
-
A.
10
-
B.
20
-
C.
100
-
D.
200
Solution
Linear SNR = 10^(SNR(dB)/10) = 10^(20/10) = 100.
Correct Answer: C — 100
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Q. In a communication system, what does 'multiplexing' refer to?
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A.
Combining multiple signals into one
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B.
Separating signals
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C.
Amplifying signals
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D.
Encoding signals
Solution
Multiplexing refers to combining multiple signals into one for transmission.
Correct Answer: A — Combining multiple signals into one
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Q. In a communication system, what does 'noise' refer to?
-
A.
The desired signal
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B.
Unwanted disturbances that affect the signal
-
C.
The modulation technique used
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D.
The bandwidth of the channel
Solution
Noise refers to unwanted disturbances that interfere with the desired signal, affecting the quality of communication.
Correct Answer: B — Unwanted disturbances that affect the signal
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Q. In a communication system, what does 'signal-to-noise ratio' (SNR) measure?
-
A.
The strength of the signal relative to background noise
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B.
The total power of the signal
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C.
The bandwidth of the communication channel
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D.
The efficiency of the modulation technique
Solution
Signal-to-noise ratio (SNR) measures the strength of the signal relative to the background noise, indicating the quality of the communication.
Correct Answer: A — The strength of the signal relative to background noise
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Q. In a compound microscope, which lens is the eyepiece?
-
A.
Convex lens
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B.
Concave lens
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C.
Bifocal lens
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D.
Plano-convex lens
Solution
The eyepiece of a compound microscope is a convex lens.
Correct Answer: A — Convex lens
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Q. In a compound microscope, which lens is the objective lens?
-
A.
The lens closest to the eye
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B.
The lens closest to the object
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C.
The lens with the longer focal length
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D.
The lens with the shorter focal length
Solution
The objective lens is the one closest to the object being viewed.
Correct Answer: B — The lens closest to the object
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Q. In a concentration cell, if the concentration of one half-cell is 0.1 M and the other is 1 M, what is the cell potential?
-
A.
0.059 V
-
B.
0.118 V
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C.
0.0591 V
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D.
0.1181 V
Solution
Using the Nernst equation, E = (0.0591/n) log([C1/C2]), where n=1.
Correct Answer: B — 0.118 V
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Q. In a concentration cell, the potential difference arises due to:
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A.
Different temperatures
-
B.
Different concentrations
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C.
Different pressures
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D.
Different materials
Solution
In a concentration cell, the potential difference arises due to different concentrations of the same species.
Correct Answer: B — Different concentrations
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Q. In a conical pendulum, if the angle of the string with the vertical is increased, what happens to the horizontal component of the tension?
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A.
Increases
-
B.
Decreases
-
C.
Remains the same
-
D.
Becomes zero
Solution
As the angle increases, the horizontal component of tension increases to provide the necessary centripetal force.
Correct Answer: A — Increases
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Q. In a cyclic process, the change in internal energy is:
-
A.
Positive
-
B.
Negative
-
C.
Zero
-
D.
Depends on the path taken
Solution
In a cyclic process, the system returns to its initial state, so the change in internal energy is zero.
Correct Answer: C — Zero
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Q. In a cyclic process, the change in internal energy of the system is:
-
A.
Positive
-
B.
Negative
-
C.
Zero
-
D.
Depends on the work done
Solution
In a cyclic process, the system returns to its initial state, so the change in internal energy is zero.
Correct Answer: C — Zero
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Q. In a cyclic process, the net work done by the system is equal to:
-
A.
The net heat added to the system
-
B.
The change in internal energy
-
C.
The heat lost by the system
-
D.
Zero
Solution
In a cyclic process, the net work done by the system is zero because the system returns to its initial state.
Correct Answer: D — Zero
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Q. In a cyclic process, the net work done is equal to the:
-
A.
Change in internal energy
-
B.
Heat added to the system
-
C.
Heat removed from the system
-
D.
Net heat transfer
Solution
In a cyclic process, the net work done is equal to the heat added to the system.
Correct Answer: B — Heat added to the system
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Q. In a cyclic process, the net work done is equal to: (2020)
-
A.
Net heat added
-
B.
Change in internal energy
-
C.
Zero
-
D.
Net heat removed
Solution
In a cyclic process, the net work done is equal to the net heat added to the system, as the internal energy returns to its initial state.
Correct Answer: A — Net heat added
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Q. In a cyclic process, what is the net change in internal energy of the system?
-
A.
Positive
-
B.
Negative
-
C.
Zero
-
D.
Depends on the path taken
Solution
In a cyclic process, the system returns to its initial state, so the net change in internal energy is zero.
Correct Answer: C — Zero
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Q. In a cyclic process, what is the net change in internal energy?
-
A.
Positive
-
B.
Negative
-
C.
Zero
-
D.
Depends on the process
Solution
In a cyclic process, the system returns to its initial state, so the net change in internal energy is zero.
Correct Answer: C — Zero
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Q. In a damped harmonic oscillator, if the amplitude decreases to half its initial value in 4 seconds, what is the damping ratio?
-
A.
0.25
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B.
0.5
-
C.
0.75
-
D.
1.0
Solution
The damping ratio can be calculated using the logarithmic decrement method, leading to ζ = 0.25.
Correct Answer: A — 0.25
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Q. In a damped harmonic oscillator, if the damping coefficient is increased, what happens to the amplitude of oscillation?
-
A.
Increases
-
B.
Decreases
-
C.
Remains the same
-
D.
Becomes zero
Solution
In a damped harmonic oscillator, increasing the damping coefficient results in a decrease in the amplitude of oscillation over time.
Correct Answer: B — Decreases
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Q. In a damped harmonic oscillator, if the damping coefficient is increased, what happens to the time period of oscillation?
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A.
Time period increases
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B.
Time period decreases
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C.
Time period remains the same
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D.
Time period becomes zero
Solution
The time period of a damped harmonic oscillator remains the same; damping affects amplitude, not period.
Correct Answer: C — Time period remains the same
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Q. In a damped harmonic oscillator, if the mass is doubled while keeping the damping coefficient constant, what happens to the damping ratio?
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A.
Doubles
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B.
Halves
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C.
Remains the same
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D.
Increases by a factor of √2
Solution
Damping ratio (ζ) = c / (2√(mk)). If m is doubled, ζ is halved.
Correct Answer: B — Halves
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Q. In a damped harmonic oscillator, what effect does increasing the damping coefficient have on the oscillation?
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A.
Increases amplitude
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B.
Decreases amplitude
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C.
Increases frequency
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D.
Decreases frequency
Solution
Increasing the damping coefficient results in a decrease in amplitude over time, leading to quicker energy loss.
Correct Answer: B — Decreases amplitude
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Q. In a damped harmonic oscillator, what happens to the amplitude of oscillation over time?
-
A.
Increases
-
B.
Decreases
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C.
Remains constant
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D.
Oscillates
Solution
In a damped harmonic oscillator, the amplitude of oscillation decreases over time due to energy loss.
Correct Answer: B — Decreases
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Q. In a damped harmonic oscillator, what happens to the amplitude over time? (2023)
-
A.
Increases
-
B.
Decreases
-
C.
Remains constant
-
D.
Oscillates
Solution
In a damped harmonic oscillator, the amplitude decreases over time due to energy loss.
Correct Answer: B — Decreases
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Q. In a damped harmonic oscillator, which factor primarily determines the rate of energy loss?
-
A.
Mass of the oscillator
-
B.
Spring constant
-
C.
Damping coefficient
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D.
Frequency of oscillation
Solution
The damping coefficient determines how quickly the energy is lost in a damped harmonic oscillator.
Correct Answer: C — Damping coefficient
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Q. In a damped harmonic oscillator, which of the following quantities decreases over time?
-
A.
Amplitude
-
B.
Frequency
-
C.
Angular frequency
-
D.
Phase constant
Solution
In a damped harmonic oscillator, the amplitude decreases over time due to the energy lost to damping forces.
Correct Answer: A — Amplitude
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Q. In a damped harmonic oscillator, which of the following statements is true?
-
A.
Energy is conserved
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B.
Amplitude decreases over time
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C.
Frequency increases over time
-
D.
Phase remains constant
Solution
In a damped harmonic oscillator, the amplitude decreases over time due to the loss of energy.
Correct Answer: B — Amplitude decreases over time
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Q. In a damped harmonic oscillator, which parameter is primarily responsible for energy loss?
-
A.
Mass
-
B.
Spring constant
-
C.
Damping coefficient
-
D.
Driving force
Solution
The damping coefficient determines the rate of energy loss in a damped harmonic oscillator.
Correct Answer: C — Damping coefficient
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Q. In a damped harmonic oscillator, which parameter primarily determines the rate of energy loss?
-
A.
Mass of the oscillator
-
B.
Spring constant
-
C.
Damping coefficient
-
D.
Driving force
Solution
The damping coefficient determines how quickly energy is lost in a damped harmonic oscillator.
Correct Answer: C — Damping coefficient
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Q. In a damped oscillator, if the energy decreases to 25% of its initial value in 10 seconds, what is the damping ratio?
-
A.
0.1
-
B.
0.2
-
C.
0.3
-
D.
0.4
Solution
Using E(t) = E_0 e^(-2ζω_nt), we find ζ = 0.2.
Correct Answer: B — 0.2
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Q. In a Daniell cell, which metal acts as the anode?
-
A.
Copper
-
B.
Zinc
-
C.
Silver
-
D.
Lead
Solution
In a Daniell cell, Zinc acts as the anode.
Correct Answer: B — Zinc
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