Electric Charges and Fields

Physics Chapter 1: Electric Charges and Fields

Electric Charge: A property of particles due to which they experience electric force. Two types: positive and negative.
Properties of Charge: Additive, Quantized (q = ±ne), and Conserved.
Coulomb’s Law: F = k * |q1*q2| / r², where k = 1 / (4πε₀).
Superposition Principle: Net force on a charge is vector sum of forces from all other charges.
Electric Field: E = F/q, vector quantity, direction is force on positive test charge.
Field due to Point Charge: E = kq / r², radially outward (positive q) or inward (negative q).
Electric Dipole: Two equal and opposite charges separated by a small distance.
Dipole Moment: p = q × 2a, direction from - to + charge.
Electric Flux: Φ = E·A = EAcosθ, measure of electric field through surface.
Gauss’s Law: Φ = q/ε₀, total flux through closed surface equals charge enclosed divided by ε₀.

What is the SI unit of electric charge?
- A. Coulomb ✅
- B. Ampere
- C. Newton
- D. Farad
Two charges +q and -q placed a distance d apart form:
- A. A monopole
- B. An electric field
- C. An electric dipole ✅
- D. None of these
Which law is used to find electric field due to symmetrical charge distribution?
- A. Coulomb's Law
- B. Gauss's Law ✅
- C. Faraday's Law
- D. Ampere's Law
Electric field due to a point charge decreases:
- A. Linearly with distance
- B. Inversely with distance
- C. Inversely with square of distance ✅
- D. Remains constant
Electric flux through a closed surface depends on:
- A. Total charge enclosed ✅
- B. Area of the surface
- C. Shape of surface
- D. Position of charges outside the surface