CSS Physics chapter 2: Heat, electricity and light MCQs with answers
By Team Megalecture · Updated 4 Nov 2026
64 exam-style questions on Heat, electricity and light, each with the answer and a short explanation. Ten of them are below to try. The chapter test draws ten fresh questions each time and is marked the moment you finish, with your score by topic.
Electrostatics and current electricity16 questions
Magnetism, induction and Maxwell's equations16 questions
Optics16 questions
Ten Heat, electricity and light questions with answers
Try each one, then open the answer. These ten stay the same; the test draws new ones every time.
1. Which of these electromagnetic waves has the highest frequency?
A
microwaves
B
infrared radiation
C
ultraviolet light
D
radio waves
Show answer
Answer: C. In order of increasing frequency the spectrum runs radio, microwave, infrared, visible, ultraviolet, X-rays and gamma rays.
2. Two identical resistors are connected across the same battery, first in series and then in parallel. The total power dissipated in the parallel connection compared with the series connection is
A
twice as large
B
the same
C
one quarter as large
D
four times as large
Show answer
Answer: D. With a fixed voltage V, P = V2/Req. Series: Req = 2R; parallel: Req = R/2. The ratio is 2R/(R/2) = 4.
3. A transparent material has a refractive index of 2. The critical angle for light travelling from this material into air is
A
45°
B
60°
C
90°
D
30°
Show answer
Answer: D. sin C = n2/n1 = 1/2, so C = 30°. For light going from the material to air, incidence beyond this angle gives total internal reflection.
4. A particle of charge 2 μC moves at 103 m s−1 at right angles to a uniform magnetic field of 0.5 T. The magnetic force on it is
A
2 × 10−3 N
B
1 × 10−3 N
C
1 × 10−6 N
D
0
Show answer
Answer: B. F = qvB sin 90° = (2 × 10−6)(103)(0.5) = 1 × 10−3 N. The force would be zero only if v were parallel to B.
5. In an electromagnetic wave in vacuum the electric field amplitude is 300 V m−1. Taking c = 3 × 108 m s−1, the amplitude of the magnetic field is
A
9 × 1010 T
B
1 × 10−10 T
C
9 × 10−6 T
D
1 × 10−6 T
Show answer
Answer: D. In vacuum E/B = c, so B = 300/(3 × 108) = 1 × 10−6 T.
6. A proton and an alpha particle (mass four times, charge twice that of the proton) enter the same uniform magnetic field at right angles with the same speed. The ratio (radius of alpha path)/(radius of proton path) is
A
4
B
1/2
C
8
D
2
Show answer
Answer: D. r = mv/(qB). The alpha particle has m larger by 4 and q larger by 2, so its radius is 4/2 = 2 times greater.
7. A Wheatstone bridge is balanced with P = 10 Ω and Q = 20 Ω in the two ratio arms, and R = 15 Ω in the third arm. The unknown resistance S in the fourth arm is
A
7.5 Ω
B
15 Ω
C
30 Ω
D
45 Ω
Show answer
Answer: C. At balance P/Q = R/S, so S = RQ/P = 15 × 20/10 = 30 Ω. Inverting the ratio gives 7.5 Ω.
8. At a point inside a uniformly charged thin spherical shell (not at its surface), the electric field is
A
constant, but not zero
B
kQ/r2 measured from the centre
C
greatest at the centre
D
zero
Show answer
Answer: D. A Gaussian surface inside the shell encloses no charge, so by symmetry the field is zero everywhere in the cavity.
9. A reversible process transfers 600 J of heat into a system at a constant temperature of 300 K. The change of entropy of the system is
A
+200 J K−1
B
+0.5 J K−1
C
+2 J K−1
D
−2 J K−1
Show answer
Answer: C. ΔS = Qrev/T = 600/300 = +2 J K−1. Multiplying instead of dividing would give a value of 180 000.
10. According to the third law of thermodynamics, as the temperature of a perfect crystal approaches absolute zero its entropy
A
approaches zero
B
approaches infinity
C
approaches its maximum value
D
becomes negative
Show answer
Answer: A. A perfect crystal has a single microstate at 0 K, so S = k ln 1 = 0. A related consequence is that absolute zero cannot be reached in a finite number of steps.
Heat, electricity and light: questions students ask
How many Heat, electricity and light MCQs are there?
64, each with the answer and a short explanation, across 4 topics: Thermodynamics and kinetic theory, Electrostatics and current electricity, Magnetism, induction and Maxwell's equations, Optics. Every chapter test draws ten of them, so you can take it many times.
Is the CSS Physics chapter 2 test free?
Yes. The test, the answers and the explanations are free and need no sign-up. Sign in only if you want your scores kept across devices.
How is the chapter test marked?
The moment you press Finish: your score, the right answer and an explanation for every question, and the ones you got wrong saved in My mistakes to retry.
