Project Prepared by

Sukanti Majhi class-viiiManaswini Padhi class-viii

Govt. Girls High School Koraput

WHY DOES AN ELECTRIC BULB GIVE LESS LIGHT THAN A TUBE LIGHT?

• In an ordinary bulb, due to the high resistance of tungsten filament the electric current makes the filament so hot (about 2100 degree Celsius) that it glows light yellow, which then turns into a point-source of yellowish light.

WHY DOES AN ELECTRIC BULB GIVE LESS LIGHT THAN A TUBE LIGHT?

• Whereas the operating principle of a tube-light is completely different.

• The long tube with mercury vapour filling and a coating of fluorescent material in its inner wall contains two filaments at the two ends.

• The flow of electrons between the filaments causes radiation from the mercury atoms.

WHY DOES AN ELECTRIC BULB GIVE LESS LIGHT THAN A TUBE LIGHT?

• When this radiated energy comes in contact with the fluorescent coating, it emits white or near-white light.

• Since the whole surface is the source of light, the emitted light gets intensified as compared to the ordinary bulb.