Suggested practical - investigation of reflection with a mirror
Aim of the experiment
To investigate the reflection of light by a plane mirror.
Method
- Set up a ray box, slit and lens so that a narrow ray of light is produced.
- Place a 30 centimetre (cm) ruler near the middle of a piece of plain A3 paper. Draw a straight line parallel to its longer sides. Use a protractor to draw a second line at right angles to this line. Label this line with an 'N' for 'normal'.
- Place a A mirror with a flat, smooth, reflective surface. against the first line.
- Use the ray box to shine a ray of light at the point where the normal meets the mirror. This is the Light ray moving towards a surface or boundary..
- The angle between the normal and the incident ray is called the Angle between the normal and the incident ray.. Move the ray box or paper to change the angle of incidence. The aim is to see a clear ray reflected from the surface of the mirror.
- Using a pencil on the paper, mark the path of:
- the incident ray with a cross
- the Light ray leaving a surface or boundary. with a cross
- Remove the mirror. Join the crosses to show the paths of the light rays.
- Measure the angle of incidence and angle of reflection for the mirror.
- Repeat steps 2 - 8 for several different angles of incidence.
Results
Record results in a suitable table.
| Attempt | Angle of incidence (°) | Angle of reflection (°) |
| 1 | 35 | 35 |
| 2 | 16 | ... |
| 3 | ... | ... |
| Attempt | 1 |
|---|---|
| Angle of incidence (°) | 35 |
| Angle of reflection (°) | 35 |
| Attempt | 2 |
|---|---|
| Angle of incidence (°) | 16 |
| Angle of reflection (°) | ... |
| Attempt | 3 |
|---|---|
| Angle of incidence (°) | ... |
| Angle of reflection (°) | ... |
Analysis
Compare the angle of incidence with the angle of reflection for each block.
Evaluation
The light rays should obey the In reflection at a surface, the angle of incidence equals the angle of reflection. for every attempt. To what extent do the results show this?
Risks/hazards
| Hazard | Consequence | Control measures |
| Ray box gets hot | Minor burns | Do not touch bulb and allow time to cool |
| Semi-dark environment | Increased trip hazard | Ensure environment is clear of potential trip hazards before lowering lights |
| Hazard | Ray box gets hot |
|---|---|
| Consequence | Minor burns |
| Control measures | Do not touch bulb and allow time to cool |
| Hazard | Semi-dark environment |
|---|---|
| Consequence | Increased trip hazard |
| Control measures | Ensure environment is clear of potential trip hazards before lowering lights |