Practical Experiment
- Light Waves: Reflection and Refraction.
Background information.
As we know, light travels from one place to another as waves. We can use equipment
such as a light box kit to investigate how light waves interact when reflecting and
refracting. Light box kits contain concave (curved inwards) objects, convex (curved
outwards) objects, prisms and planes that can be used to demonstrate how light is
reflected or refracted.
Name: Penelope Tsirogiannis
Partners: Vanessa Galea and Jake Farrugia.
Aim: The aim of the experiment is to visibly see light waves travelling using reflection and
refraction while utilising the lightbox kits and different surfaces.
Hypothesis: It is hypothesised that the experiment will demonstrate reflection and
refraction with the light waves of energy by using the light box kits to create a beam of
light that can reflect or refract depending on the different surfaces used, such as
concave, convex, plane, lens or prisms.
Materials:
- Light box kit
- Convex and concave lenses
- Prisms and planes
- Battery pack
- White A4 paper
Method:
Set up of light box kit.
1. Connect your lightbox to your battery pack as shown by your teacher.
2. Place the black plastic light distributor down with the single open shaft facing
downwards.
3. Place a sheet of white paper down in front of the light box.
4. Choose a coloured square of your choice.
5. Close the sides of the box making sure no light escapes.
Experiment 1.
6. Place a concave mirror in front of the light box and fill in the table below.
7. Flip over the concave mirror so it faces backwards and fill in the table below.
8. Place down the plane mirror so that it faces the light box and fill in the table below.
Experiment 2.
9. Place the concave lense in front of the light box (on the horizontal) and fill in the
table below.
10. Place the convex lense in front of the light box (on the horizontal) and fill in the
table below.
11. Place down the rectangular plane in front of the light box (on the diagonal) and fill
in the table below.
12. Place the prism in front of the light box and fill in the table below.
Experiment 3.
13. Start with a convex lens and hold it close to your eye. Slowly move the lense away
from your face until your arm is completed outstretched. Record what you see in
the space below.
The convex lense made the object appear larger through the lens.
14. Repeat the action for concave lenses and describe the difference between the two
lenses.
The concave lens enlarges the object and makes the object appear upside down.
Results:
Experiment 1- Light box experiment demonstrating reflection and refraction by using
different surfaces:
Top view
What happened to the
Plane, convex or concave
rays? Reflection or
surface?
refraction?
The rays are being reflected Concave surface
off the concave surface.
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Experiment 2.
The rays are once again
being reflected by the
concave surface.
Concave surface
The rays are also being
reflected by the plane
surface.
Plane surface
Top view
What happens to the rays?
Reflection or refraction?
The ray went straight
through the lens and it
refracted.
Lens or prism? Convex or
concave?
Convex lens
The rays of light travelled
straight through the lens
which means that it was
refraction.
Convex lens
The rays went straight
through but also reflected
some light so therefore it
was both reflection and
refraction.
Rectangular plane
The light went through the
triangular prism and broke
of in two directions which
makes it refraction. The
light scattered.
Triangular prism
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Discussion:
Question 1: Describe the difference between reflection and refraction based on what you
saw in your results.
The difference between reflection and refraction is that with reflection, the light bounces
off the object and with refraction, the light rays travel straight through.
Question 2: Describe the effect concave and convex lenses have on the light that passes
through them.
Both the concave and convex lenses had the same effect which was refraction meaning
that they both made the light to go straight through.
Question 3. Does the distance from the object alter the way the light bends? Explain your
response.
The distance from the object does indeed alter the way that the light bends because it
makes the light sharper and closer together.
Question 4. The following image demonstrates what feature of light waves and why?
The image shows reflection and also appears to be scattering because the light is
travelling in two different directions.
Conclusion: ​
(Summarise the experiment, refer to and describe results, state if the
hypothesis was support or not and why and acknowledge any errors made and how they
could have impacted results).
In conclusion, the experiment that was completed in class provided a visual
representation of how light waves interact when reflecting and refracting. It was
discovered that by using different surfaces or lenses, it affects whether the light reflects
or refracts. The predicted hypothesis was correct, and the experiment did indeed
demonstrate reflection and refraction whilst using the light box kits and different
surfaces/lenses. Using a concave surface enforced the rays to reflect off the concave
surface, whereas using a convex surface made the ray travel directly through the lens
and it then refracted. An interesting component was that using a triangular prism made
the light go through the triangular prism and broke of in two directions which is called
scattering and also makes it refraction. It was also identified when looking through the
convex and concave lenses, that the convex lens made the object appear larger through
the lens whereas the concave lens enlarged the object and made the object appear
upside down. The results may have been affected by the scattering of other light sources
such as the sky light and other windows in the room, and the colour of the colour cards
may have also affected the experiments because different colours would have different
opacities.