10 April 2011

Short Questions - 2

1. Why fluorescent tube light is considered better than tungsten filament-bulb?

Answer :
The luminous efficiency of tungsten filament lamp is ~ 3 % while that of fluorescent tube light is nearly 9 %. Therefore the tube light gives 3 times more luminously than a filament bulb for same consumption of electric power.

2. Why there is summer in December and Winter in June in Southern hemisphere?

Answer :

In Southern hemisphere the angle of incidence of sun rays is minimum in December and maximum in June. Hence there is summer in December and winter in June.
3. Why a photographer uses a red bulb in his dark room?

Answer :

In visible light the red colour has maximum wavelength and minimum energy. Therefore red light does not affect the photographic film.