Light Practical GCSE Physics Experiment
Investigate the reflection of light by different types of surfaces and the refraction of light by different substances.
During this required practical, students will use a ray box to produce a narrow beam of light to trace the path of light when it is reflected from and refracted through blocks made of different materials (e.g. Perspex and glass). They will compare this between the different materials available. Low light conditions are required for this practical procedure.
Equipment (per pair of participants)
• Ray optics box
• Bench power supply
• Rectangular glass block
• Rectangular Perspex block
• 30cm ruler
• Protractor
• Plain A3 paper
Method
- Prepare the Paper and Block
- Use a ruler to draw a straight line in the centre of the paper.
- Align the block of material with this centre line and trace around it to ensure consistent placement throughout the experiment.
- Draw the Normal Line
- Use a protractor to draw a line at a 90-degree angle to the centre line, approximately at the block's midpoint.
- Label this line ‘N’ to indicate the normal, which will align with the light beam from the ray box.
- Set Up the Ray Box
- Adjust the ray box to produce a narrow beam of light.
- Position the ray box so the light beam meets the point where the normal line (‘N’) intersects the edge of the block. Ensure the beam exiting the block is also narrow.
- Trace the Light Beam Path
- Mark the path of the incoming light beam with small crosses.
- Repeat this for the path of the light beam exiting the opposite side of the block.
- Draw the Light Rays
- Turn off the ray box to prevent overheating.
- Remove the block and connect the crosses with straight lines to show the three light rays:
- The incoming ray
- The refracted ray (inside the block)
- The outgoing ray
- Label the Rays
- Use appropriate scientific terms to label each ray on the diagram.
- Measure and Record the Angles
- Use a protractor to measure the angles of incidence, reflection, and refraction.
- Record these measurements in a table.
- Repeat with a Different Material
- Replace the block with one made of a different material and repeat Steps 3–7.
Technician tips
- Low light conditions are preferable for this practical. Total black-out should not be required.
- In order to improve visibility for students, a large box could be placed over the ray box and paper whilst the students take their measurements. Large printer paper boxes are ideal for this.
To do this practical you will need
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