LIGHT AND SOUND

LIGHT - FACTS TO REMEMBER

* The speed of light is 300,000,000 m/s

* Colour of light with smallest wavelength      -      Violet

* Colour of light with longest wavelength       -     Red

* Three dimensional imaging using interference of light is known as         -      Holography

* System of light excitation used in surgeries, printers etc      -       LASER

* The colour of light which is most conducive to photosynthes        -      Blue

*  The study of properties and behaviour of light is known as       -      Optics

SOUND - FACTS TO REMEMBER

* The speed of sound is 343 m/s.

* The level of sound prolonged exposure beyond which may cause permanent hearing loss     -     85 dBA

* Woman’s voice is shriller than a man’s voice because of higher Pitch

* The animals which produce sounds of high pitch and frequency to communicate and locate each other      -     Dolphins and elephants

* The loudness of sound is measured in       -    Decibels

* The minimum distance which is required to hear an echo        -     17 metres

* The system of sound reflection used to find the depth of oceans       -     SONAR (Sound navigation ranging)

* The phenomenon which makes the sound of an approaching train shriller       -     Doppler effect

* Sounds cannot travel in vacuum 

* Sounds travel faster in metals than in air

* Sonic boom occurs when a super sonic aircraft crosses the sound barrier