Question

Explain why,filament-type electric bulbs are not power efficient.Name any two types of electric lighting devices which are must much more energy efficient than filament-type bulbs.

Answer 1

In filament type electric bulb, we get light when the filament heats up and begins to glow. A large amount of electrical energy is lost as heat. So, this kind of bulb is energy efficient or power efficient. The filament in a filament type bulb is made of tungsten. It works on the following principle - current when passing through the filament turns it into red colour, then yellow and lastly yellowish white, which is the colour of light we get. In this procedure, extra heating results in most of the power - more than 90% - getting wasted in the form of heat. Therefore, they have lower power efficiency. Alternatives to filament type bulbs include halogen bulbs and LEDs.