Investigating Light

• This is the first of two investigations in this topic that you'll come across. They're both to do with the behaviour of light.
• For both experiments, you'll need a ruler, protractor and a nice sharp pencil
• It's best to do these experiments in a dim room so you can clearly see paths of the rays of light.
• They both use either a ray box or a laser to produce thin rays of light. This is so you can trace the paths of the rays more accurately, meaning more exact angle measurements.
• Refraction


  The bending of light as it passes from one medium to another
• Investigating refraction


  1. Place a transparent rectangular block on paper and trace around it

  2. Use a ray box or laser to shine a ray of light at the middle of one side of the block

  3. Trace the incident ray and mark where the light ray emerges on the other side

  4. Remove the block and join up the incident ray and emerging point to show the refracted ray

  5. Draw the normal at the point where the light ray entered the block

  6. Measure the angle of incidence and angle of refraction
• The angle of refraction changes for different materials due to their different optical densities
• Reflection


  The bouncing back of light from a surface
• Investigating reflection


  1. Draw a straight line on a piece of paper

  2. Place an object so one side lines up with the line

  3. Shine a ray of light at the object's surface and trace the incoming and reflected light beams

  4. Draw the normal at the point where the ray hits the object

  5. Measure the angle of incidence and angle of reflection
• Smooth surfaces like mirrors give clear reflections, while rough surfaces cause diffuse reflection which makes the reflected beam wider and dimmer
• The angle of incidence always equals the angle of reflection