Investigating Light

You need to do both of these experiments in a dim room

Both experiments use rays of light, so it’s best to do them in a dim room so you can clearly see the light rays. They also both use either a ray box or a laser to produce thin rays of light. This is so you can easily see the middle of the rau when tracing it and measuring angles from it.

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You can use transparent materials to investigate refraction

The boundaries between different substances refract light by different amounts. You can investigate this by looking at how much light is refracted when it passes from air into different materials

• Place a transparent rectangular block on a piece of paper and trace around it. Use a ray box or a laser to shine a ray of light at the middle of one side of the block

• Trace the incident ray and mark where the light ray emerges on the other side of the block. Remove the block and, with a straight line, join up the incident ray and the emerging point to show the path of the refracted ray through the block

• Draw the normal at the point where the light ray entered the block. Use a protractor to measure the angle between the incident ray and the normal and the angle between the refracted ray and the normal

• Repeat this experiment using rectangular blocks made from different materials, keeping the incident angle the same throughout

  You should find that the angle of refraction changes for different materials-this difference is due to their different optical densities

Different materials reflect light by different amounts

• Take a piece of paper and draw a straight line across it. Place an object so one of its sides lines up with this line
• Shina a ray of light at the object’s surface and trace the incoming and reflected light beams
• Draw the normal at this point where the ray hits the object. Use a protractor to measure the angle of incidence and the angle of reflection and record these values in a table. Also make a note of the width and brightness of the reflected light ray
• Repeat this experiment for a range of objects

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