## Revision Notes of Ch 12 Electricity and Circuits Class 6th Science

Topics in the chapter

• Electricity
• Source of electrical energy
• Electric current
• Source of electric current
• Flow of electric current
• Electric circuit and types of circuit
• Component of electricity
• Conductor and insulator

Electricity

→ It is a set of physical phenomena which involves an electrical charge.

What causes an electrical charge?

It is caused by an imbalance in positive or negative charge.

Source of electrical energy

→ Electrical energy is available to us from electric power houses, domestic generators, dry cells and batteries.

Electric current

→ It is a flow of electric charges, these electric current flows in one direction only.

→ Examples: oven, room heater, ceiling fan and electric bulb work when an electric current flows through them.

Source of electric current

→ It is a device which is used to produce an electric current is called a source of electric current.

→ Common sources of electric current are cells and batteries which comes in various shapes and sizes and electric current that we get from plug points in houses.

Flow of electric current

→ Cell, battery or a plug point acting as a source.

→ Copper, silver or aluminium wires allow electric current flow easily.

→ An unbroken loop (of the wire) running from one terminal of the source, through various appliances, back to the other terminal of the source.

Electric circuit

→ It provides a path through which electricity travels from one terminal of the cell through the bulb and back to the other terminal of the cell is called electric circuit.

Examples

→ Some electric circuits in the natural world
• Nerves in our body create electric circuit
• Lightning, clouds and planet earth form an electric circuit

→ Some man- made electric circuits are:
• Wiring that lights our house
• Car battery, ignition switch and starter in a car.

Type of circuits

(i) Closed circuits

→ It is unbroken path travelled by electricity is known as a closed circuit it is also known as complete circuit.

→ If the circuit is complete or closed, the bulb lights up.

→ The direction of flow of electricity is from the positive terminal of the cell to the negative terminal of the cell.

(ii) Open circuits

→ It is broken path by which electricity cannot pass is known as open circuit also known as incomplete body.

→ A bulb will not light up if there is a gap in circuit. If the circuit is open the bulb will not light up.

Component of electricity

(i) Connecting wires: It helps to conduct the electric current and complete the circuit.

(ii) Bulb: when circuit is complete the lights up.

(iii) Battery: it is a series combination of two or more cells.

(iv) Switch: a switch works by breaking or completing the circuit path.
→ Switch on: The circuit path is complete.
→ Switch off: the circuit path is broken.

(v) Electric cell or dry cell

→ An electric cell has two terminals; one is called positive while the other is negative.

→ Inside the electric cell, the electric charges flows from negative terminal to the positive terminal.

→ Connecting wires, bulb, switch and electric cell is used in torch, battery, LED etc.

Conductor and insulator

(i) Conductor:

→ Materials which allow electric current passes through it, is known as conductor.

→ All metals are good conductor, only non-metal which is good conductor for electricity is carbon.

→ A few non-metals like graphite (pencil lead is made of graphite) are also conductors of electricity.

(ii) Insulator

→ Materials which do not allow electric current passes through it.

→ Examples: plastic, elastic etc.

→ The handles of screwdrivers and testers used by electricians are usually made of wood or hard plastic.