Science [ 5 Marks Questions ]

S.No.	CONDUCTORS	INSULATORS
1.	Alumtnium	Wood
2.	Earth	Plastic
3.	Copper	Rubber
4.	Iron	Glass
5.	Sea water	Eraser

Sl.no.	Electric component	Figure	Symbol
1.	Electric cell	Cell
2.	Battery	Battery
3.	Switch-open		Open
4.	Switch-closed		Close
5.	Electric bulb
6.	Connecting wires
7.	Connecting wires

1. In thermal power stations, thermal energy is generated by burning coal, diesel, or gas to produce steam.
2. Steam is used to rotate the turbine to generate electricity.
3. Here heat energy is converted into electric energy.

• Hydel power stations:

1. In hydel power stations, the turbine is made to rotate by the flow of water from dams.
2. Here kinetic energy is converted into electric energy.

• Atomic power station:

1. Here nuclear energy is used to boil water
2. The steam thus produced is used to rotate the turbine, as a result, electricity is produced.
3. Here nuclear energy is converted into mechanical energy.

• Windmills:

1. In windmills, wind energy is used to rotate turbines to produce electricity.
2. Here kinetic energy is converted into electrical energy.

Safety measures to safeguard a person from electric shock:
Switch off the power supply.
Remove the connection from the switch.
Push him away using non-conducting materials.
Give him first aid and take him to the nearest health centre.

A device that converts chemical energy into electrical energy is called a cell. Cells are classified, in two types. They are-

1. Primary cells,
2. Secondary cells.

1. Primary cells:

• They can not be recharged.
• They can be used only once.
• They are small in size.
• Eg. Cells used in clocks, watches, and toys, etc.

2. Secondary cells:

• A cell that can be recharged many times is called secondary cells.
• Depending upon usage size may vary.
• Eg. Secondary cells are used in mobile phones, laptops, emergency lamps, and vehicle batteries.