Light 2

• We see objects because light travels out from a source to them
• Light can bounce or reflect off an object
• Some materials are transparent which means they transmit light energy through them
• Translucent materials let only some of the light through
• Opaque reflects and absorbs the light energy instead of transmitting it
• Rough surfaces disperse or scatter the light
• Light energy radiates or travels out in all direction from the light source
• The speed of light is much faster that the speed of sound
• We show the path that light has travelled in a diagram by drawing a straight line called a ray
• We can see objects because they reflect the light
• Light does not need medium to travel through
• Light bounces or reflects from a plane surface in a predictable way
• The incident ray arrives at the surface
• The reflected ray leaves
• The angle of incidence is equal to the angle of reflection measured from the normal line
• Mirrors give an inverted, at the normal line the same distance as the original shape. Perpendicular
• Refraction is the bending of a light ray as it passes from one transparent substance( medium) to another.
• Light travels at different speeds through different media
• 300 million meters per second In air
• 200 million meters per second in glass
• When light slows down from one medium to another light ray bends towards the normal
• When light speeds up from one medium to another light ray bends away from the normal
• Spectru— the bands of colored light seen prism disperse sunlight. The colors include red, orange, yellow, green , blue , indigo, violet
• White light from sun contains light at different wavelengths which give different colored light
• Light waves of different wavelengths travel at different speeds through the prism
• They disperse to form colours of the spectrum
• Light waves with shortest wavelengths are lowed down and refracted the most
• Rainbow is produced by refraction and reflection of the suns light through water drops
• Primary colors of light are green red and blue
• Secondary colors of light are yellow magenta and cyan
• When rays of sunlight strike a surface, the different colors may be absorbed or reflected
• Absorbed-objects appears black
• Reflected-object appears white
• most objects absorbs some color and reflect others
• Sheets of colored plastic or glass can filter colors of light allowing some colors to be absorbed and others to pass through.
• Law of reflection is angle of incidence=angle of refraction
• When light is reflect ed in lots of different directions , we know It as scattering
• materials tht do not let light pass through are opaque
• Refraction is the bending of light when It reaches a transparent medium. The light slows down a using It to change direction
• different objects have different colours because of light,the colours might be absorbeD oR transmitted.Some colours have different wavelengths