physics

• Light


  Made up of particles called photons
• Light


  Is an electromagnetic wave
• Light does not need a medium
• The electromagnetic spectrum shows all types of electromagnetic waves e.g. gamma rays, radio waves and visible light
• Electromagnetic waves


  Transverse waves that transfer energy perpendicularly to electric and magnetic fields
• Wave model


  Explains how light moves as a wave using wavelengths, frequency, and speed
• Particle model


  Explains how light moves as a particle using photons
• The speed of light is constant in any given medium; nothing travels faster than light
• In a vacuum, the speed of light is 3.0x10^8 ms-1
• Mechanical wave


  Moves through a medium or a substance
• Electromagnetic waves


  Light energy that photons travel through that does not require a medium
• Surface wave


  A wave that moves perpendicular to the direction of the wave is moving
• Transverse waves


  Move perpendicular to the direction of the wave
• Longitudinal waves


  Move in a direction parallel to the wave
• Luminous objects


  Can produce light on their own
• Non-luminous objects


  Do not produce or refract bright light
• Non-luminous objects can only be seen if they refract light coming from luminous objects
• Reflection


  1. Incident wave

  2. Reflection wave
• During reflection, the wave speed, frequency and wavelength do not change
• If the wave is parallel to the surface when it hits, it will be reflected back in the direction it came from
• If the wave hits the surface at an angle, its direction of travel will change
• Refraction


  The process of incident rays at a boundary changing direction & speed when passing into a new medium
• When light moves from air into glass, it slows down and changes direction towards the normal
• When light moves from a glass block into air, it speeds up and changes direction away from the normal
• Snell's law


  Describes how light bends when it passes from one medium to another
• Medium


  The material or substance through which a wave can travel by transferring energy
• Concave lens


  Spreads/bends out light rays
• Convex lens


  Bends together light rays
• Convex lens turns everything upside down in our eye but our brain flips it the right way up
• Principal focus


  The point where parallel rays of light converge after passing through a convex lens
• Focal length


  The distance between the center of the lens and the principal focus
• Diffraction


  The process where waves either bend behind a barrier or the wavefront is broken up into many small sources
• Interference


  The combination of two or more waves forming a resultant wave
• Constructive interference


  Occurs when waves move the same way, making the wave bigger
• Destructive interference


  Occurs when waves cancel each other out
• Average acceleration = final speed – initial speed / time taken