Physics
Q. In which direction does the magnetic field line emerge from a bar magnet? (2022)
A.
From North to South
B.
From South to North
C.
In a circular path
D.
Randomly
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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)
A.
[T^-1]
B.
[M^0 L^0 T^-1]
C.
[M^1 L^1 T^-1]
D.
[M^0 L^1 T^0]
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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)
A.
[M^0 L^1 T^-1]
B.
[M^1 L^1 T^0]
C.
[M^1 L^0 T^-1]
D.
[M^0 L^0 T^1]
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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)
A.
0 degrees
B.
90 degrees
C.
180 degrees
D.
45 degrees
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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)
A.
The particle moves parallel to the field
B.
The particle moves perpendicular to the field
C.
The particle is at rest
D.
The particle moves in a circular path
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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 fork? (2019)
A.
0.00227 s
B.
0.0045 s
C.
0.01 s
D.
0.005 s
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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 frequency of a tuning fork is 440 Hz. What is the time period of the sound wave produced? (2022)
A.
0.00227 s
B.
0.0045 s
C.
0.01 s
D.
0.005 s
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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)
A.
Amplitude
B.
Wavelength
C.
Frequency
D.
Period
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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)
A.
f = 1/(2π√(LC))
B.
f = 2π√(LC)
C.
f = LC
D.
f = R/(2πL)
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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)
A.
Coulomb
B.
Ampere
C.
Volt
D.
Ohm
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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)
A.
They disappear
B.
They become weaker
C.
Each piece becomes a magnet with its own field
D.
They merge into one
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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 strength inside a solenoid if the number of turns is increased? (2023)
A.
It decreases
B.
It remains the same
C.
It increases
D.
It becomes zero
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Solution
The magnetic field strength inside a solenoid increases with the number of turns, as it is directly proportional to the number of turns per unit length.
Correct Answer: C — It increases
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Q. What happens to the magnetic field when the current in a solenoid is reversed? (2023)
A.
It remains the same
B.
It disappears
C.
It reverses direction
D.
It doubles
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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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Q. What happens to the magnetic field when the distance from a long straight conductor is doubled? (2023)
A.
It doubles
B.
It halves
C.
It remains the same
D.
It quadruples
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Solution
The magnetic field around a long straight conductor decreases with distance. Specifically, it is inversely proportional to the distance from the conductor.
Correct Answer: B — It halves
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Q. What is the base unit of temperature in the SI system? (2020)
A.
Celsius
B.
Fahrenheit
C.
Kelvin
D.
Rankine
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Solution
The base unit of temperature in the SI system is Kelvin (K).
Correct Answer: C — Kelvin
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Q. What is the capacitance of a capacitor that stores 10 µC of charge at a potential difference of 5 V?
A.
2 µF
B.
5 µF
C.
10 µF
D.
20 µF
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Solution
C = Q/V = 10 × 10^-6 C / 5 V = 2 × 10^-6 F = 2 µF.
Correct Answer: A — 2 µF
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Q. What is the capacitive reactance of a capacitor of 10μF at a frequency of 60 Hz? (2016)
A.
265.26Ω
B.
159.15Ω
C.
100Ω
D.
50Ω
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Solution
Capacitive reactance Xc = 1 / (2πfC) = 1 / (2π * 60 * 10e-6) = 265.26Ω.
Correct Answer: A — 265.26Ω
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Q. What is the capacitive reactance of a capacitor with a capacitance of 10μF at a frequency of 50Hz? (2020)
A.
318.31 ohms
B.
159.15 ohms
C.
31.83 ohms
D.
15.92 ohms
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Solution
Xc = 1 / (2πfC) = 1 / (2π × 50 × 10 × 10^-6) = 318.31 ohms.
Correct Answer: A — 318.31 ohms
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Q. What is the change in entropy when 1 kg of water at 100°C is converted to steam at 100°C? (Latent heat of vaporization = 2260 kJ/kg) (2021)
A.
2260 J/K
B.
2260 kJ/K
C.
0 J/K
D.
1130 J/K
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Solution
ΔS = Q/T = 2260 kJ / 373 K = 6.06 kJ/K.
Correct Answer: A — 2260 J/K
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Q. What is the change in internal energy of a gas that absorbs 300 J of heat and does 100 J of work on the surroundings? (2020)
A.
200 J
B.
300 J
C.
400 J
D.
500 J
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Solution
Change in internal energy (ΔU) = Q - W = 300 J - 100 J = 200 J.
Correct Answer: A — 200 J
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Q. What is the change in internal energy of a system if 200 J of heat is added and 50 J of work is done by the system?
A.
150 J
B.
250 J
C.
200 J
D.
100 J
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Solution
Using the first law of thermodynamics, ΔU = Q - W = 200 J - 50 J = 150 J.
Correct Answer: A — 150 J
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Q. What is the change in internal energy of a system if 300 J of heat is added and 100 J of work is done by the system? (2021)
A.
200 J
B.
300 J
C.
400 J
D.
500 J
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Solution
Using the first law of thermodynamics: ΔU = Q - W = 300 J - 100 J = 200 J.
Correct Answer: A — 200 J
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Q. What is the current through a 10Ω resistor connected to a 20V battery? (2020)
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Solution
Using Ohm's law, I = V/R = 20V / 10Ω = 2A.
Correct Answer: B — 2A
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Q. What is the current through a 12Ω resistor connected to a 24V battery? (2023)
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Solution
Using Ohm's law, I = V/R = 24V / 12Ω = 2A.
Correct Answer: B — 2A
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Q. What is the current through a 12Ω resistor when a voltage of 48V is applied? (2023)
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Solution
Using Ohm's law, I = V/R = 48V / 12Ω = 4A.
Correct Answer: B — 6A
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Q. What is the current through a 15Ω resistor connected to a 45V source? (2021)
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Solution
Using Ohm's law, I = V/R = 45V / 15Ω = 3A.
Correct Answer: A — 3A
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Q. What is the direction of the magnetic field around a straight conductor carrying current? (2023)
A.
From north to south
B.
Clockwise
C.
Counterclockwise
D.
Radially outward
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Solution
The direction of the magnetic field around a straight conductor carrying current is counterclockwise when viewed from the positive end of the conductor.
Correct Answer: C — Counterclockwise
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Q. What is the direction of the magnetic field inside a bar magnet? (2023)
A.
From south to north
B.
From north to south
C.
Circular
D.
Random
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Solution
The direction of the magnetic field inside a bar magnet is from the north pole to the south pole.
Correct Answer: B — From north to south
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Q. What is the effect of a dielectric material on the capacitance of a capacitor? (2023)
A.
It decreases the capacitance
B.
It increases the capacitance
C.
It has no effect
D.
It makes the capacitor discharge
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Solution
Inserting a dielectric material increases the capacitance of a capacitor by reducing the electric field within it.
Correct Answer: B — It increases the capacitance
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Q. What is the effect of increasing the capacitance in a capacitive AC circuit on the current? (2022)
A.
Increases current
B.
Decreases current
C.
No effect
D.
Current becomes zero
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Solution
Increasing capacitance increases the current in a capacitive AC circuit, as current I = V/Xc.
Correct Answer: A — Increases current
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