Light and Sound

Light and Sound

Properties of Light

  • Light is a form of electromagnetic wave which can be detected by the human eye.
  • Light travels in straight lines and this property is used in explaining how shadows are formed.
  • The speed of light in vacuum is approximately 3 x 10^8 metres per second.
  • Reflection of light happens when light bounces off an object. The law of reflection states that the angle of incidence is equal to the angle of reflection.
  • Light can refract or bend when it moves from one medium to another. This bending is due to a change in the speed of light.
  • Converging lenses bring parallel rays of light together at a point known as the focus. Diverging lenses diverge parallel rays of light.
  • The colour of an object is determined by the colours of light it absorbs and the colours it reflects.

Properties of Sound

  • Sound is a form of longitudinal wave created by vibrating objects.
  • The speed of sound is slower than the speed of light; in air, it is approximately 343 metres per second.
  • Sound needs a medium to travel; it cannot travel through vacuum.
  • The pitch of a sound is how high or low it sounds, and it’s determined by the frequency of the sound wave.
  • Loudness of a sound is related to the amplitude of the sound waves. The larger the amplitude, the louder the sound.
  • Echoes are due to reflection of sound waves from a surface.
  • Ultrasound waves have frequencies above the range of human hearing and have various applications including in medicine and sonar.

With a good understanding of these properties of light and sound, you’ll be equipped to tackle a range of related topics and problems.