Q. A ray of light passes from air into glass at an angle of 45 degrees. What is the angle of refraction if the refractive index of glass is 1.5? (2022)
Q. A refrigerator removes heat from the inside at a rate of 200 J/s and expels it to the surroundings at a rate of 250 J/s. What is the coefficient of performance (COP) of the refrigerator? (2023)
Q. A rotating object has an angular momentum L. If its moment of inertia is halved and angular velocity is doubled, what is the new angular momentum? (2022)
A.L
B.2L
C.3L
D.4L
Solution
L = Iω, if I is halved and ω is doubled, L' = (1/2)(2ω) = L.
Q. A simple pendulum oscillates with a period of 2 seconds. What is the length of the pendulum? (2021)
A.0.5 m
B.1 m
C.2 m
D.4 m
Solution
The period T of a simple pendulum is given by T = 2π√(L/g). Rearranging gives L = (T^2 * g) / (4π^2). Using g = 9.8 m/s² and T = 2 s, we find L = (2^2 * 9.8) / (4π^2) ≈ 1 m.
Q. A solenoid produces a magnetic field similar to that of a bar magnet. What is the primary factor that determines the strength of the magnetic field in a solenoid? (2021)
A.Length of the solenoid
B.Number of turns per unit length
C.Material of the solenoid
D.Current flowing through the solenoid
Solution
The strength of the magnetic field in a solenoid is primarily determined by the number of turns per unit length and the current flowing through it.
Correct Answer: B — Number of turns per unit length
Q. A solenoid produces a magnetic field similar to that of a bar magnet. What is the main factor that affects the strength of the magnetic field in a solenoid? (2021)
A.Length of the solenoid
B.Number of turns per unit length
C.Material of the solenoid
D.Current flowing through the solenoid
Solution
The strength of the magnetic field in a solenoid is primarily affected by the number of turns per unit length and the current flowing through it.
Correct Answer: B — Number of turns per unit length
Q. A solid sphere of radius R rolls without slipping down an incline of height h. What is its speed at the bottom of the incline? (2021)
A.√(2gh)
B.√(3gh)
C.√(4gh)
D.√(5gh)
Solution
Using conservation of energy, potential energy at the top = kinetic energy at the bottom. For a solid sphere, v = √(5gh/7). Thus, speed at the bottom is √(3gh).
Q. A solid sphere of radius R rolls without slipping down an inclined plane of height h. What is the speed of the center of mass at the bottom of the incline? (2021)
A.√(2gh)
B.√(3gh)
C.√(4gh)
D.√(5gh)
Solution
Using conservation of energy, potential energy at height h = kinetic energy at the bottom. For a solid sphere, v = √(3gh).
