1. Concept Overview
Electrostatics is the study of how electric charges behave when they are not moving. Even if a charge is completely still, it creates an influence around itself that can push or pull other charges. Many small daily-life effects—like dust sticking to a screen or a spark from a metal door handle—come from electrostatic interactions. This topic sets the base for ideas like electric field, potential, dipoles and capacitors.
2. Definition
Electrostatics is the branch of physics that deals with electric charges at rest and the forces and fields produced by them.
3. Key Ideas
Here are the core ideas that help build intuition about electrostatics:
3.1. Nature of Electric Charge
- Charge comes in two types: positive and negative.
- Like charges repel and unlike charges attract.
- Charge is a basic property of matter, similar to mass.
3.2. Forces Without Contact
A charged object can exert a force on another object without touching it. This happens because every charge creates an electric field around it that extends outward and fills the surrounding space.
3.3. Conductors and Insulators
- Conductors allow charges to move freely (like metals).
- Insulators do not allow charges to move easily (like rubber or glass).
The behaviour of charges depends a lot on whether the material lets them move or keeps them fixed.
3.4. Strength of Electric Force
The electric force between charges is extremely strong compared to gravity. Even tiny amounts of charge can create noticeable effects, which is why electrostatic phenomena are common in everyday situations.
4. Everyday Examples
Electrostatics shows up often, even in simple objects:
4.1. Balloon Sticking to a Wall
After rubbing a balloon on hair, it picks up charge and sticks to a wall because of the attraction between the charged balloon and the neutral wall surface.
4.2. Charged Comb Attracting Paper Bits
Rubbing a plastic comb makes it charged, and the charge pulls tiny paper pieces towards it.
4.3. Sparks on Touching Metal
Sometimes, charge builds up on the body. When touching a metal object, this charge suddenly moves, creating a small spark.
4.4. Dust Sticking to Screens
Screens often accumulate charge, which attracts dust particles floating in the air.
5. Physical Interpretation
One way to visualise electrostatics is to imagine that every charge creates an invisible field around it. When another charge enters this field, it experiences a push or pull. The idea of the electric field helps explain interactions without physical contact. Understanding this simple picture makes later topics—like potential, flux and Gauss’s law—much easier to grasp.