Q. The unit of energy in the SI system is equivalent to which of the following? (2020)
A.
Joule
B.
Newton-meter
C.
Both A and B
D.
None of the above
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Solution
Energy is measured in Joules, and 1 Joule is defined as 1 Newton-meter, hence both A and B are correct.
Correct Answer:
C
— Both A and B
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Q. What happens to the capacitance of a parallel plate capacitor if the distance between the plates is increased? (2020)
A.
It increases
B.
It decreases
C.
It remains the same
D.
It becomes zero
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Solution
The capacitance (C) of a parallel plate capacitor is inversely proportional to the distance (d) between the plates. If d increases, C decreases.
Correct Answer:
B
— It decreases
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Q. What happens to the induced current if the magnetic field is suddenly removed from a coil? (2022)
A.
It continues to flow
B.
It stops immediately
C.
It increases
D.
It decreases gradually
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Solution
If the magnetic field is suddenly removed, the change in magnetic flux becomes zero, leading to an immediate stop in the induced current.
Correct Answer:
B
— It stops immediately
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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 strength inside a solenoid if the number of turns per unit length is increased? (2023)
A.
It decreases
B.
It increases
C.
It remains the same
D.
It becomes zero
Show solution
Solution
The magnetic field strength inside a solenoid is directly proportional to the number of turns per unit length. Therefore, if the number of turns per unit length is increased, the magnetic field strength also increases.
Correct Answer:
B
— 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 current in a wire is reversed? (2023)
A.
It remains the same
B.
It doubles
C.
It reverses direction
D.
It disappears
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Solution
When the current in a wire 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 happens to the total current in a parallel circuit if one branch is removed? (2021)
A.
Increases
B.
Decreases
C.
Remains the same
D.
Depends on the branch
Show solution
Solution
Removing a branch in a parallel circuit decreases the total current.
Correct Answer:
B
— Decreases
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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
Show solution
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
Show solution
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
Show solution
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 1 mole of an ideal gas when it is heated at constant volume from 300 K to 600 K?
A.
0 J
B.
300 J
C.
600 J
D.
900 J
Show solution
Solution
ΔU = nCvΔT. For a monatomic gas, Cv = (3/2)R. ΔU = 1 * (3/2)(8.31 J/mol K)(600 - 300) = 900 J.
Correct Answer:
D
— 900 J
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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
Show solution
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
Show solution
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)
Show solution
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)
Show solution
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 connected to a 48V power supply? (2021)
Show solution
Solution
Using Ohm's law, I = V/R = 48V / 12Ω = 4A.
Correct Answer:
A
— 4A
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Q. What is the current through a 12Ω resistor connected to a 48V source? (2021)
Show solution
Solution
Using Ohm's law, I = V/R = 48V / 12Ω = 4A.
Correct Answer:
A
— 4A
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Q. What is the current through a 12Ω resistor when a voltage of 48V is applied across it? (2021)
Show solution
Solution
Using Ohm's law, I = V/R = 48V / 12Ω = 4A.
Correct Answer:
C
— 4A
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Q. What is the current through a 12Ω resistor when a voltage of 48V is applied? (2023)
Show solution
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)
Show solution
Solution
Using Ohm's law, I = V/R = 45V / 15Ω = 3A.
Correct Answer:
A
— 3A
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Q. What is the de Broglie wavelength of an electron moving with a velocity of 1 x 10^6 m/s? (mass of electron = 9.11 x 10^-31 kg) (2022)
A.
6.63 x 10^-24 m
B.
6.63 x 10^-22 m
C.
6.63 x 10^-20 m
D.
6.63 x 10^-18 m
Show solution
Solution
λ = h / p = h / (mv) = 6.63 x 10^-34 / (9.11 x 10^-31 * 1 x 10^6) = 6.63 x 10^-24 m.
Correct Answer:
A
— 6.63 x 10^-24 m
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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
Show solution
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
Show solution
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
Show solution
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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