Physics
Q. In an AC circuit, if the frequency is 60Hz and the inductance is 0.2H, what is the inductive reactance? (2021)
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A.
12.56Ω
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B.
37.68Ω
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C.
75.36Ω
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D.
100Ω
Solution
Inductive reactance (XL) = 2πfL = 2π(60)(0.2) ≈ 75.36Ω.
Correct Answer: B — 37.68Ω
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Q. In an AC circuit, if the frequency is increased, what happens to the inductive reactance? (2020)
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A.
It increases
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B.
It decreases
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C.
It remains constant
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D.
It becomes zero
Solution
Inductive reactance (XL = 2πfL) increases with an increase in frequency.
Correct Answer: A — It increases
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Q. In an AC circuit, if the power factor is 0.8, what is the angle between the voltage and current? (2020)
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A.
36.87°
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B.
53.13°
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C.
60°
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D.
45°
Solution
The angle θ can be found using cos(θ) = power factor. Therefore, θ = cos⁻¹(0.8) ≈ 36.87°.
Correct Answer: B — 53.13°
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Q. In an AC circuit, if the resistance is 10 ohms and the inductive reactance is 20 ohms, what is the impedance? (2020)
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A.
10 ohms
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B.
20 ohms
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C.
√(10² + 20²)
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D.
30 ohms
Solution
The impedance Z = √(R² + XL²) = √(10² + 20²) = √(100 + 400) = √500 = 22.36 ohms.
Correct Answer: C — √(10² + 20²)
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Q. In an AC circuit, if the resistance is 10Ω and the inductive reactance is 20Ω, what is the total impedance? (2020)
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A.
10Ω
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B.
20Ω
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C.
√(10² + 20²)
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D.
30Ω
Solution
The total impedance Z = √(R² + XL²) = √(10² + 20²) = √(100 + 400) = √500 = 22.36Ω.
Correct Answer: C — √(10² + 20²)
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Q. In an AC circuit, if the voltage is 120 V and the current is 10 A with a power factor of 0.8, what is the real power consumed? (2021)
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A.
960 W
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B.
1200 W
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C.
800 W
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D.
1000 W
Solution
Real power P = V * I * power factor = 120 * 10 * 0.8 = 960 W.
Correct Answer: A — 960 W
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Q. In an AC circuit, if the voltage is 120V and the current is 10A with a power factor of 0.8, what is the real power consumed? (2021)
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A.
120W
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B.
800W
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C.
960W
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D.
1000W
Solution
Real power P = V * I * power factor = 120V * 10A * 0.8 = 960W.
Correct Answer: C — 960W
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Q. In an AC circuit, if the voltage is 120V and the current is 10A, what is the power factor if the real power is 600W? (2022)
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A.
0.5
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B.
0.6
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C.
0.8
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D.
1.0
Solution
Power factor = Real Power / (Voltage x Current) = 600 / (120 x 10) = 600 / 1200 = 0.5.
Correct Answer: B — 0.6
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Q. In an AC circuit, if the voltage is given by V(t) = 100 sin(100t), what is the RMS voltage? (2023)
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A.
100 V
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B.
70.7 V
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C.
50 V
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D.
141.4 V
Solution
The RMS voltage is V_rms = V0/√2 = 100/√2 = 70.7 V.
Correct Answer: B — 70.7 V
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Q. In an AC circuit, if the voltage is given by V(t) = 100√2 sin(1000t), what is the peak voltage? (2023)
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A.
100 V
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B.
100√2 V
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C.
200 V
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D.
50 V
Solution
The peak voltage is given by the coefficient of sin, which is 100√2.
Correct Answer: B — 100√2 V
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Q. In an AC circuit, if the voltage is V(t) = 120 sin(ωt), what is the RMS voltage? (2017)
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A.
120 V
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B.
60 V
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C.
84.85 V
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D.
100 V
Solution
RMS voltage V_rms = V_peak / √2 = 120 / √2 = 84.85 V.
Correct Answer: C — 84.85 V
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Q. In an AC circuit, the voltage is given by V(t) = V0 sin(ωt). What is the peak voltage if V0 = 10V? (2021)
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A.
5V
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B.
10V
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C.
15V
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D.
20V
Solution
The peak voltage V0 is given directly in the equation as 10V.
Correct Answer: B — 10V
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Q. In an AC circuit, the voltage is given by V(t) = V0 sin(ωt). What is the peak voltage? (2021)
Solution
The peak voltage in the equation V(t) = V0 sin(ωt) is V0.
Correct Answer: A — V0
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Q. In an adiabatic process, the temperature of an ideal gas decreases. What happens to its pressure?
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A.
Increases
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B.
Decreases
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C.
Remains constant
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D.
Depends on volume
Solution
In an adiabatic process, as the temperature decreases, the pressure also decreases due to the ideal gas law.
Correct Answer: B — Decreases
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Q. In an RLC circuit, if the resistance is 6Ω, inductive reactance is 8Ω, and capacitive reactance is 4Ω, what is the total impedance? (2021)
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A.
10Ω
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B.
12Ω
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C.
14Ω
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D.
16Ω
Solution
Total impedance Z = √(R² + (XL - XC)²) = √(6² + (8 - 4)²) = √(36 + 16) = √52 ≈ 10Ω.
Correct Answer: B — 12Ω
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Q. In an RLC circuit, if the resistance is increased, what happens to the quality factor (Q)? (2021)
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A.
Increases
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B.
Decreases
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C.
Remains the same
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D.
Becomes zero
Solution
The quality factor Q is inversely proportional to resistance. Increasing resistance decreases Q.
Correct Answer: B — Decreases
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Q. In an RLC series circuit, if the inductive reactance is greater than the capacitive reactance, the circuit is said to be: (2022)
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A.
Resonant
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B.
Inductive
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C.
Capacitive
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D.
Purely resistive
Solution
If the inductive reactance (XL) is greater than the capacitive reactance (XC), the circuit is inductive.
Correct Answer: B — Inductive
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Q. In an RLC series circuit, if the resistance is 10 Ω, inductance is 0.1 H, and capacitance is 100 μF, what is the resonant frequency? (2023)
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A.
50 Hz
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B.
100 Hz
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C.
159 Hz
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D.
200 Hz
Solution
The resonant frequency f0 = 1/(2π√(LC)) = 1/(2π√(0.1 * 100e-6)) = 159 Hz.
Correct Answer: C — 159 Hz
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Q. In an RLC series circuit, if the total impedance is 50 ohms and the resistance is 30 ohms, what is the reactance? (2020)
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A.
40 ohms
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B.
30 ohms
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C.
20 ohms
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D.
10 ohms
Solution
Using Z = √(R² + X²), we find X = √(Z² - R²) = √(50² - 30²) = √(2500 - 900) = √1600 = 40 ohms.
Correct Answer: A — 40 ohms
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Q. In which direction does the magnetic field line emerge from a bar magnet? (2022)
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A.
From North to South
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B.
From South to North
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C.
In a circular path
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D.
Randomly
Solution
Magnetic field lines emerge from the north pole and enter the south pole of a bar magnet.
Correct Answer: A — From North to South
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Q. The dimensional formula for frequency is: (2023)
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A.
[T^-1]
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B.
[M^0 L^0 T^-1]
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C.
[M^1 L^1 T^-1]
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D.
[M^0 L^1 T^0]
Solution
Frequency is defined as the number of cycles per unit time, hence its dimensional formula is [T^-1].
Correct Answer: A — [T^-1]
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Q. The dimensional formula for velocity is: (2022)
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A.
[M^0 L^1 T^-1]
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B.
[M^1 L^1 T^0]
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C.
[M^1 L^0 T^-1]
-
D.
[M^0 L^0 T^1]
Solution
Velocity is defined as displacement per unit time, hence its dimensional formula is [M^0 L^1 T^-1].
Correct Answer: A — [M^0 L^1 T^-1]
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Q. The force on a charged particle moving in a magnetic field is maximum when the angle between the velocity and the magnetic field is: (2021)
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A.
0 degrees
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B.
90 degrees
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C.
180 degrees
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D.
45 degrees
Solution
The force on a charged particle moving in a magnetic field is maximum when the angle between the velocity and the magnetic field is 90 degrees.
Correct Answer: B — 90 degrees
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Q. The force on a charged particle moving in a magnetic field is maximum when: (2021)
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A.
The particle moves parallel to the field
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B.
The particle moves perpendicular to the field
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C.
The particle is at rest
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D.
The particle moves in a circular path
Solution
The force on a charged particle moving in a magnetic field is maximum when the particle moves perpendicular to the field.
Correct Answer: B — The particle moves perpendicular to the field
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Q. The frequency of a tuning fork is 440 Hz. What is the time period of the sound wave produced? (2022)
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A.
0.00227 s
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B.
0.0045 s
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C.
0.01 s
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D.
0.005 s
Solution
Time period (T) = 1 / frequency (f) = 1 / 440 Hz ≈ 0.00227 s.
Correct Answer: A — 0.00227 s
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Q. The maximum displacement of a wave from its rest position is called what? (2022)
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A.
Amplitude
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B.
Wavelength
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C.
Frequency
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D.
Period
Solution
The maximum displacement from the rest position is defined as the amplitude of the wave.
Correct Answer: A — Amplitude
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Q. The resonant frequency of an RLC circuit is given by which formula? (2022)
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A.
f = 1/(2π√(LC))
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B.
f = 2π√(LC)
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C.
f = LC
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D.
f = R/(2πL)
Solution
The resonant frequency f of an RLC circuit is given by f = 1/(2π√(LC)).
Correct Answer: A — f = 1/(2π√(LC))
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Q. The unit of electric charge in the SI system is: (2022)
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A.
Coulomb
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B.
Ampere
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C.
Volt
-
D.
Ohm
Solution
Coulomb (C) is the SI unit of electric charge.
Correct Answer: A — Coulomb
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Q. What happens to the magnetic field lines when a magnet is cut into two pieces? (2021)
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A.
They disappear
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B.
They become weaker
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C.
Each piece becomes a magnet with its own field
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D.
They merge into one
Solution
When a magnet is cut into two pieces, each piece becomes a magnet with its own north and south poles, thus maintaining the magnetic field lines.
Correct Answer: C — Each piece becomes a magnet with its own field
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Q. What happens to the magnetic field when the current in a solenoid is reversed? (2023)
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A.
It remains the same
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B.
It disappears
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C.
It reverses direction
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D.
It doubles
Solution
When the current in a solenoid is reversed, the direction of the magnetic field also reverses.
Correct Answer: C — It reverses direction
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