MIND GROW Magazine

Electrostatics – Stage 0 (Foundation)

Chapter 1: Electric Charges & Fields – Page 4

1. What is Electric Charge?

Electric charge is a fundamental property of matter responsible for electric forces and electric fields.

Two types: Positive and Negative
Like charges repel, unlike charges attract

Foundation Rule: Charge is not created by rubbing — it is only transferred.

2. Quantization of Charge

Electric charge exists in discrete packets, not continuously.

q = n e

q = total charge
n = integer (… −3, −2, −1, 0, 1, 2, 3 …)
e = elementary charge = 1.6 × 10⁻¹⁹ C

Very Important (JEE): Fractional charge does not exist in isolation.

3. Elementary Charge (e)

The smallest free charge observed in nature is the charge of an electron or proton.

Charge of electron = −1.6 × 10⁻¹⁹ C
Charge of proton = +1.6 × 10⁻¹⁹ C

JEE Trap: Oil-drop experiment proves quantization, not value creation.

4. Conservation of Charge

The total electric charge of an isolated system always remains constant.

Meaning:

Charge cannot be created
Charge cannot be destroyed
Charge can only be transferred

JEE Law: Algebraic sum of charges before interaction = after interaction

5. Charging by Friction (Triboelectric Effect)

When two different materials are rubbed together, electrons transfer from one body to another.

One body becomes negatively charged
The other becomes positively charged

Example: Glass rod rubbed with silk → glass becomes positive

6. Charging by Conduction

Charge transfer occurs when a charged body touches a neutral conductor.

Charge redistributes
Both bodies get same type of charge

JEE Note: Conduction requires physical contact.

7. Charging by Induction

A neutral conductor can be charged without contact by a nearby charged body.

Opposite charges induced on nearer side
Same charges on farther side

High-Value JEE Concept: Induction produces opposite charge without touching.

8. Can Charge Be Fractional?

In macroscopic objects, charge is always an integer multiple of e.

Fractional charges appear only in advanced particle physics (quarks), not in classical electrostatics.

Stage 0 – Page 4 Takeaway

Charge is quantized
Charge is conserved
Elementary charge is the smallest unit
Charging methods are core JEE tools

Stage 0 – Page 4 Completed ✅