mechanical energy is converted to electrical energy 

electrical energy converted to mechanical energy

chemical energy converted to electrical enenrgy

electrical energy converted to heat energy

Switch of electrical devices after use

Ensure that street lights are switched off in time

Use lights and other equipments every time

Promote use of LEDs

Iron

Copper

Braze

Nickel

Metals are insulators

All materials are conductors

Metals are conductors

Heavy materials are conductors

Operating a switch with a dry hand.

Using wires without insulation.

Removing plug pins when the switch is off.

Changing bulbs when the switch is off.

Switch in the on mode

Fuse

Switch in the off mode

Conducting wire