Required Practicals - Reflection and Refraction Flashcards
What is the goal of the practical?
To investigate the reflection of light by different types of surface and the refraction of light by different substances
What do we use to investigate reflection?
A ray box, a lens and a slit.
This produces a narrow ray of light.
Why is it important to switch ray boxes off when not being used?
They can get very hot very quickly.
Why don’t we do the practical with a laser?
It can be more dangerous so a ray box is safer.
What are the steps for investigating reflection?
Take an A3 piece of paper and draw a straight line down the centre using a ruler.
Use a protractor to draw the line at right angles which is the normal - labelled N.
Place a glass block against the first line so that the normal is near the centre of the block.
Draw lines around the perimeter of the glass block.
Turn out all other lights in the room.
Use the ray box to direct a ray of light so it hits the block at the normal, being the incident ray.
Measure the angle of incidence using a protractor.
Adjust the ray box to change the angle of incidence.
You can see both a reflected ray and a transmitted ray at a certain angle.
Mark the path of the incident and reflected ray with crosses and the path of the transmitted ray.
Turn on the room lights and switch off the ray box.
Remove the glass block.
What is the incident ray?
The ray of light directed towards a new medium.
What is the angle of incidence?
The angle between the incident ray and the normal.
What is the transmitted ray?
The ray leaving the block of glass from the other side.
What do we do with the paper without the glass block with the different crosses for rays?
Draw in the incident and reflected ray with the crosses.
Draw in the transmitted ray so it meets the position of the block.
Draw a line to show the path of the transmitted ray through the glass block.
Which angles do we measure using a protractor?
Measure the angle of incidence and reflection.
Measure the angle of refraction against the normal inside the block.
How do we repeat the experiment?
Follow the same steps but use a block made from a different material like a plastic such as Perspex.
What should we discover about angles of incidence and reflection?
They should be the same for both the glass and the Perspex.
Why are angles of incidence and reflection the same for both blocks?
They do not depend on the material.
What will we find out about angle of refraction?
It will be different with Perspex than with glass.
Why will the angle of refraction be different with different materials?
The angle of refraction is dependent on the material.
