The Speed of a Wave is affected by the Density of the Substance or Medium its Travelling in. When crossing througha Boundary between Two Different Substances it will change Speed.
Wave Speed = Frequency X Wavelength
Frequency is Fixed for each Type of Wave, so when Speed Changes, Wavelength also Changes (Decreasing Speed = Decreasing Wavelength)
Changes in Speed and Wavelength can cause a change in Direction : Refraction.
Focus Points + Images:
- Converging or Convex Lenses use Refraction to Focus Light Waves to Form an Image of the Object.
The Light Ray hits the Lens Surface and Passes from Air to Glass, causing it to Slow Down which in turn causes the Light…