Lighting effect of electric current SSLC physics chapter one

Lamps show lighting effect of electric current. There are several types of lamps . Incandescent lamps,discharge lamps,fluorescent lamps,LED lamps etc. Let us discuss some of them here

Incandescent Lamps

Incandescent lamps are simply called filament lamps. It is not common in these days. A filament lamp is having a glass cover and a tungsten filament connected with copper wire inside the glass cover

Working : When current passes through the tungsten filament , it will heated up quickly to white hot condition and emit white light. To avoid oxidation of tungsten, it is kept inside the evacuated glass chamber. And vaporization can be reduced by filling Nitrogen inside the glass covering. 

Why tungsten?

Tungsten has chosen because of its..

• high resistivity.
• high melting pont
• high ductility
• Ability to emit whit light in white hot condition

major part of the electrical energy in Incandescent lamp is lost as heat. Hence the efficiency of this lamp is very low.

Discharge lamps

Working: Discharge lamp consist of a glass tube , In which gas is being filled. At the ends of this tube , We have two electrodes. When we apply high potential in these electrodes, the gas molecules will get excited . The molecules will absorb the energy end the electrons will go to higher energy state. While coming back from this high energy state it will release this energy . According to this energy levels different colors will emit from the lamp.

LED ( Light emitting diode)

LEDs are constructed using semiconductors. According to the semiconductor materials used for manufacturing LED, It will emit different colors.

It consumes very less amount of power . And as it is not using any chemical inside the lamp, it is less harmful to the Environment.

Construction Of LED Lamps

The figure above shows the main components used for making a LED lamp. And We can assemble the LED by the following procedure.

6 steps to construct LED Lamp

1. fix the base unit by punching it on to the heat sink 
2. cover the power supply board using insulation tapes in such away that the input and output supply wires will be visible but will not get covered with dust or moisture.
3. Fix the wires seen on the input part of the power supply to the back conductor,by passing it through heat sink and terminal holes.
4. Fix the red wire in the output into the part marked positive in the board and the black wire into the negative marking.
5. apply heat sink compound at the back of the LED Printed circuit board and then fix it on the base plate.
6. Press and close the heat sink by using the diffuser cup. And make sure that the LED bulb thus made emits light when fixed to the bub holder

And we can easily get the Idea of how to make LED lamp in 6 steps by looking into the below Image