Electric Charges and Fields is a Class 12 Physics chapter that carries about 2.8% of the Physics questions in NEET. Practise it with 40 questions covering 2 topics, each with an explanation.
Sample questions on Electric Charges and Fields with answers
8 questions from the practice bank, spread across the chapter's topics. The full set is in the app.
Question 1: Coulomb's Law
The ratio of the electrostatic force to the gravitational force between two electrons is of the order of:
- A 10¹²
- B 1
- C 10⁻⁴²
- D 10⁴²
Answer: D. 10⁴²
Why: The electric force is enormously larger than the gravitational force at the atomic scale.
Question 2: Electric Field, Field Lines and Gauss's Law
The electric field inside a uniformly charged hollow conducting sphere is:
- A maximum at the center
- B zero everywhere inside
- C equal to the field outside
- D infinite
Answer: B. zero everywhere inside
Why: By Gauss's law, since no charge is enclosed within any Gaussian surface drawn inside a hollow conducting sphere (all charge resides on the outer surface), the electric field inside is zero.
Question 3: Coulomb's Law
Two identical conducting spheres carry charges of +6 μC and +2 μC. They are touched together and separated. Each now carries:
- A +3 μC
- B +4 μC
- C +2 μC
- D +8 μC
Answer: B. +4 μC
Why: The charge is shared equally between identical spheres, so (6 + 2)/2 = 4 μC.
Question 4: Electric Field, Field Lines and Gauss's Law
A closed surface contains no net charge. The net electric flux through it is:
- A positive
- B negative
- C infinite
- D zero
Answer: D. zero
Why: By Gauss's law, the flux is q_enclosed/ε₀ = 0.
Question 5: Coulomb's Law
The SI unit of the electric dipole moment is:
- A coulomb metre
- B newton metre
- C volt per metre
- D coulomb per metre
Answer: A. coulomb metre
Why: p = q × 2a, a charge multiplied by a distance, so its unit is C m.
Question 6: Electric Field, Field Lines and Gauss's Law
The electric field at a distance r from an infinitely long line charge with a linear density λ is:
- A λr/ε₀
- B λ/(2πε₀r)
- C λ/(4πε₀r²)
- D λ/(2ε₀)
Answer: B. λ/(2πε₀r)
Why: E ∝ 1/r for a line charge.
Question 7: Coulomb's Law
Two point charges, each of magnitude q, are separated by a distance r in vacuum and experience a mutual force F. If the distance is halved, the new force is:
- A F/4
- B F/2
- C 2F
- D 4F
Answer: D. 4F
Why: Coulomb's force follows F ∝ 1/r². Halving the distance increases the force by a factor of 4.
Question 8: Electric Field, Field Lines and Gauss's Law
Inside a uniformly charged non-conducting solid sphere, the electric field at a distance r from the centre varies as:
- A 1/r²
- B 1/r
- C r
- D r²
Answer: C. r
Why: The charge enclosed is proportional to r³, and the area to r², so E ∝ r.