Maheswari

did textbook

Definition:

Electricity is a type of energy caused by the movement of tiny particles called electrons.

Examples:

1. When you switch on a bulb, electricity makes it glow.

2. A fan spins because electricity powers its motor.

3. Televisions and computers work using electricity.

Definition 

Force is a push or pull on an object that can make it move, stop, or change direction.

Example

Pushing a door, pulling a rope, or kicking a ball are all examples of force.

Definition

An electromagnet is a magnet that works only when electricity flows through it

Examples

1. Electric bell

2. Fan motor

3. Speakers

Definition

Gravity is a natural force that pulls all objects toward each other

Examples

1. An apple falling from a tree

2. people staying on the ground instead of floating away

3. Rain drops falling from the sky

Definition

Thermal expansion is when a material becomes bigger on heating and smaller on cooling.

Examples

1. Bridges have small gaps so they can expand in heat.

2. Railway tracks have gaps to stop bending in hot weather.

3. Jar lids loosen when heated because the metal expands.

• Surface tension is like thin skin on liquid.

• It is caused by molecules pulling each other.

• Molecules inside are pulled in all directions.

• Molecules on the surface are pulled inward.

• This makes the surface tight.

• Small insects can walk on water.