Reflection

• Their are two ray the incident ray and the reflection ray
• When something is reflected the light goes to the mirror to my eyes then to the retnia and back to the mirror thats how you see yourself in a mirror
• Things that are reflected are in the same shape,size and position but left and right is swapped
• Convex lenses have positive focal length because they focus light rays
• Concave lens have negative focal length becuase it disperses light rays
• A concave lens has diverging power so its called a diverging lens
• Refraction happens when light changes direction as it passes from one medium into another
• The refractive index of glass is higher than air so the speed of light slows down
• Light travels faster through water than glass so the refractive index of water is lower than glass
• When light travels through different materials at different speeds,it bends or refracts
• When light enters a denser material, it bends towards the normal line
• When light leaves a less dense material, it bends away from the normal line
• If the angle of incidence is less than the critical angle then total internal reflection does not occur
• Critical angle is the maximum angle that light can be incident on a surface without being totally internally reflected
• If the angle of incidence is greater than the critical angle then total internal reflection occurs
• Red has the longest wavelength and violet has the shortest wavelength
• Total internal reflection happens when light waves are trapped inside a glass prism because they cannot escape due to the high speed of light within the glass
• Total internal reflection occurs when the angle of incidence is greater than the critical angle
• The human eye cannot see ultraviolet or infra-red radiation
• Infrared radiation is used to detect objects by heating them up
• Ultraviolet radiation is used as a sterilising agent because it kills bacteria
• X-rays have very low penetration power so they do not pass through thicker objects like bones
• Gamma rays have very high penetrating power so they can penetrate thicker objects such as concrete walls