Reflection and refraction

• A boundary is the edge of a medium.
• Wherever the incident ray meets the surface is where we assume the normal is.
• The law of reflection states that the angle of incidence will always equal the angle of reflection.
• At a boundary between two media, waves change in a direction. A denser median will slow the light down.
• Refracted means bent or changed direction
• When light travels from one medium to another it changes speed and direction at the same time.
• The speed of light= 3 x 10^8 m/s
• How to do the reflection required practical:

  • Set up mirror on line on paper
  • Draw a normal
  • Mark on incident lines at 20,30 and 40 degrees
  • Direct light along the lines
  • Mark on the reflected beam and measure the angle
• What is a virtual image?

  An image that cannot be projected onto a screen or touched
• Refraction is when light passes from one medium to another it changes direction and speed.
• If a light ray hits the block at an angle, its speed and direction changes. Once through the object, the ray is bent back into its original direction and it leaves the block.
• Refraction required practical:

  • Put the rectangle prism in the middle of the page
  • Draw around it
  • Mark the normal
  • Mark a point on the side you're shining the ray and always shine the ray here
  • Shine one ray at 10 degrees from the normal
  • Draw where the ray comes out from the other side
  • Take the prism off the page and join the two lines together in the middle
  • Repeat for 20, 30, 40, 50, 60, 70 and 80 degrees
• Sources of error for the reflection practical:

  • Mirror not placed on the line between readings
  • Judgement needed to mark on reflected ray as it is wider