Physics
Q. If the inductive reactance of a coil is 30Ω and the resistance is 10Ω, what is the total impedance? (2018)
A.
10Ω
B.
30Ω
C.
33.33Ω
D.
40Ω
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Solution
Total impedance Z = √(R² + (XL)²) = √(10² + 30²) = √(100 + 900) = √1000 = 31.62Ω.
Correct Answer: C — 33.33Ω
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Q. If the latent heat of fusion of ice is 334 J/g, how much heat is required to melt 50 g of ice? (2019)
A.
1670 J
B.
3340 J
C.
5000 J
D.
1000 J
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Solution
Heat required = mass × latent heat = 50 g × 334 J/g = 16700 J.
Correct Answer: A — 1670 J
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Q. If the magnetic field strength is doubled, what happens to the force experienced by a current-carrying conductor? (2022)
A.
It doubles
B.
It halves
C.
It remains the same
D.
It quadruples
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Solution
The force experienced by a current-carrying conductor in a magnetic field is directly proportional to the magnetic field strength. Therefore, if the magnetic field strength is doubled, the force also doubles.
Correct Answer: A — It doubles
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Q. If the magnetic field strength is doubled, what happens to the force on a current-carrying conductor in that field? (2022)
A.
It doubles
B.
It halves
C.
It remains the same
D.
It quadruples
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Solution
The force on a current-carrying conductor is directly proportional to the magnetic field strength, so if the field strength is doubled, the force also doubles.
Correct Answer: A — It doubles
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Q. If the magnetic field strength is doubled, what happens to the force on a current-carrying conductor? (2022)
A.
It doubles
B.
It halves
C.
It remains the same
D.
It quadruples
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Solution
The force on a current-carrying conductor is directly proportional to the magnetic field strength, so if the magnetic field strength is doubled, the force also doubles.
Correct Answer: A — It doubles
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Q. If the mass of the Earth were to double, what would happen to the gravitational force experienced by an object on its surface?
A.
It doubles
B.
It halves
C.
It quadruples
D.
It remains the same
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Solution
Gravitational force is directly proportional to mass. If mass doubles, force also doubles.
Correct Answer: A — It doubles
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Q. If the radius of the Earth were to increase by 50%, what would happen to the weight of an object on its surface?
A.
It increases by 50%
B.
It increases by 25%
C.
It decreases by 25%
D.
It remains the same
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Solution
Weight is inversely proportional to the square of the radius. If radius increases by 50%, weight decreases by 25%.
Correct Answer: C — It decreases by 25%
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Q. If the radius of the Earth were to increase while keeping its mass constant, what would happen to the value of g? (2023)
A.
g increases
B.
g decreases
C.
g remains the same
D.
g becomes zero
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Solution
If the radius increases while mass remains constant, g decreases because g = G * M / r^2.
Correct Answer: B — g decreases
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Q. If the radius of the Earth were to increase while keeping its mass constant, what would happen to the gravitational acceleration at its surface?
A.
It increases
B.
It decreases
C.
It remains the same
D.
It becomes zero
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Solution
Gravitational acceleration g = GM/R². If R increases, g decreases.
Correct Answer: B — It decreases
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Q. If the resistance of a conductor is doubled, what happens to the current flowing through it when the voltage remains constant? (2022)
A.
Doubles
B.
Halves
C.
Remains the same
D.
Increases by 1.5 times
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Solution
According to Ohm's law, I = V/R. If R is doubled, I will be halved.
Correct Answer: B — Halves
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Q. If the speed of light in a vacuum is 3 x 10^8 m/s, what is its speed in water (n = 1.33)?
A.
2.26 x 10^8 m/s
B.
2.25 x 10^8 m/s
C.
2.27 x 10^8 m/s
D.
2.28 x 10^8 m/s
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Solution
The speed of light in a medium is given by v = c/n. Thus, v = (3 x 10^8 m/s) / 1.33 ≈ 2.26 x 10^8 m/s.
Correct Answer: A — 2.26 x 10^8 m/s
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Q. If the speed of light in a vacuum is approximately 3 x 10^8 m/s, what is its value in km/s?
A.
300 km/s
B.
3000 km/s
C.
30000 km/s
D.
300000 km/s
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Solution
To convert m/s to km/s, divide by 1000. Therefore, 3 x 10^8 m/s = 300000 km/s.
Correct Answer: D — 300000 km/s
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Q. If the speed of light in vacuum is 3 x 10^8 m/s, what is its speed in glass (n = 1.5)?
A.
2 x 10^8 m/s
B.
2.5 x 10^8 m/s
C.
3 x 10^8 m/s
D.
1.5 x 10^8 m/s
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Solution
The speed of light in a medium is given by v = c/n. Therefore, v = (3 x 10^8 m/s) / 1.5 = 2 x 10^8 m/s.
Correct Answer: A — 2 x 10^8 m/s
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Q. If the total current in an AC circuit is 5A and the voltage is 120V, what is the impedance? (2023)
A.
24Ω
B.
20Ω
C.
30Ω
D.
15Ω
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Solution
Impedance (Z) = Voltage (V) / Current (I) = 120V / 5A = 24Ω.
Correct Answer: B — 20Ω
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Q. If the voltage across a capacitor in an AC circuit is 100 V and the capacitive reactance is 50 Ω, what is the current through the capacitor? (2021)
A.
2 A
B.
0.5 A
C.
5 A
D.
10 A
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Solution
Using Ohm's law, I = V/Xc = 100 V / 50 Ω = 2 A.
Correct Answer: B — 0.5 A
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Q. If the voltage across a capacitor in an AC circuit is 100V and the capacitive reactance is 50Ω, what is the current through the capacitor? (2023)
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Solution
Current (I) = Voltage (V) / Capacitive Reactance (XC) = 100V / 50Ω = 2A.
Correct Answer: B — 2A
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Q. If the voltage across a capacitor in an AC circuit is 100V and the capacitive reactance is 50Ω, what is the current? (2021)
A.
2A
B.
0.5A
C.
5A
D.
100A
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Solution
Using Ohm's law, I = V/Xc = 100V/50Ω = 2A.
Correct Answer: B — 0.5A
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Q. If the voltage across a capacitor in an AC circuit is 100V and the capacitive reactance is 50 ohms, what is the current? (2023)
A.
2A
B.
0.5A
C.
5A
D.
10A
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Solution
Using Ohm's law, I = V/Xc = 100V/50Ω = 2A.
Correct Answer: A — 2A
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Q. If the voltage across a capacitor is 100V and the capacitive reactance is 50 ohms, what is the current through the capacitor? (2022)
A.
2 A
B.
1 A
C.
0.5 A
D.
0.25 A
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Solution
I = V/Xc = 100/50 = 2 A.
Correct Answer: B — 1 A
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Q. If the voltage across a resistor is 240V and the resistance is 60 ohms, what is the current flowing through it? (2020)
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Solution
I = V / R = 240V / 60Ω = 4A.
Correct Answer: C — 6A
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Q. If the voltage across a resistor is halved, what happens to the current through it? (2020)
A.
It doubles
B.
It halves
C.
It remains the same
D.
It quadruples
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Solution
According to Ohm's law, if voltage is halved and resistance remains constant, the current also halves.
Correct Answer: B — It halves
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Q. If the volume of a gas is doubled at constant temperature, what happens to its pressure?
A.
It doubles
B.
It halves
C.
It remains the same
D.
It quadruples
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Solution
According to Boyle's Law, at constant temperature, pressure is inversely proportional to volume. Therefore, if the volume is doubled, the pressure is halved.
Correct Answer: B — It halves
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Q. If the volume of a gas is halved at constant temperature, what happens to its pressure? (2023)
A.
It doubles
B.
It halves
C.
It remains the same
D.
It quadruples
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Solution
According to Boyle's Law, if the volume is halved, the pressure doubles at constant temperature.
Correct Answer: A — It doubles
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Q. If the volume of a gas is halved while keeping the temperature constant, what happens to the pressure of the gas?
A.
Halves
B.
Doubles
C.
Remains the same
D.
Increases by 50%
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Solution
According to Boyle's Law, if the volume is halved, the pressure doubles.
Correct Answer: B — Doubles
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Q. If the wavelength of light used in a diffraction grating is increased, what happens to the angular separation of the fringes? (2023)
A.
Increases
B.
Decreases
C.
Remains the same
D.
Becomes zero
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Solution
The angular separation (θ) is directly proportional to the wavelength (λ). Therefore, increasing λ increases the angular separation.
Correct Answer: A — Increases
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Q. If the wavelength of light used in a double-slit experiment is increased, what happens to the fringe separation? (2022)
A.
Increases
B.
Decreases
C.
Remains the same
D.
Becomes zero
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Solution
Fringe separation is directly proportional to the wavelength. If the wavelength increases, the fringe separation also increases.
Correct Answer: A — Increases
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Q. If the wavelength of light used in a single-slit diffraction experiment is increased, what will happen to the position of the first minimum? (2022)
A.
It moves closer to the center
B.
It moves away from the center
C.
It remains unchanged
D.
It disappears
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Solution
The position of the first minimum in single-slit diffraction is given by a sin(θ) = λ. Increasing λ will cause θ to increase, moving the minimum away from the center.
Correct Answer: B — It moves away from the center
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Q. If two charges +Q and -Q are placed at a distance 'd' apart, what is the electric field at the midpoint? (2020)
A.
0
B.
kQ/d^2
C.
kQ/(2d^2)
D.
kQ/d
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Solution
At the midpoint, the electric fields due to +Q and -Q cancel each other out, resulting in a net electric field of 0.
Correct Answer: A — 0
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Q. If two identical capacitors of 4 µF each are connected in series, what is the equivalent capacitance?
A.
2 µF
B.
4 µF
C.
6 µF
D.
8 µF
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Solution
C_eq = 1 / (1/C1 + 1/C2) = 1 / (1/4 + 1/4) = 2 µF.
Correct Answer: A — 2 µF
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Q. If two resistors of 4Ω and 6Ω are connected in series, what is the total resistance? (2023)
A.
10Ω
B.
24Ω
C.
2.4Ω
D.
12Ω
Show solution
Solution
In series, R_eq = R1 + R2 = 4Ω + 6Ω = 10Ω.
Correct Answer: A — 10Ω
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