Light Flashcards
What is the ‘Law of Reflection’?
The angle of incidence is equal to the angle of reflection.
What is the incident ray?
The ray that falls on a surface.
What is the reflected ray?
The ray that bounces off the surface.
What is the ‘normal’?
The line at right-angles to the surface.
What is the angle of incidence?
The angle, i, between the incident ray and the normal.
What is the angle of reflection?
The angle, r, between the reflected ray and the normal.
What are the properties of an image formed in a plane mirror?
- It is the same size as the object.
- Same distance behind the mirror as the object in front.
- It is a virtual image.
- It is laterally inverted, but always inverted.
What is refraction?
The bending of light when it goes from one material to the next due to a change in speed in the different materials.
What is the refracted ray?
The ray after it has been bent.
What is the angle of refraction?
The angle, r, between the refracted ray and the normal.
In refraction, what can you say about the ray of light before it enters the Perspex box (INCIDENT RAY) and the ray after it leaves the block (EMERGENT RAY)?
They are parallel.
What two criteria makes things directly proportional on a graph?
-If it is a straight line
-If it passes through the origin
How could you improve a refraction of light experiment?
-Repeat the experiment
-Use a narrower slit to produce a narrower beam (more accurate)
-Tun off lights and close the blinds
Finish the sentence: When light enters a Perspex block, it bends…?
Towards the normal.
Finish the sentence: When light leaves a Perspex block, it bends…?
Away from the normal.
When does light slow down?
When it enters a denser medium such s water or glass and it is refracted TOWARDS the normal.
When does light speed up?
When it passes from glass or water into air, a less dense medium and is refracted AWAY FROM the normal.
Does light travel faster in water or glass? Why?
Water because glass is denser than water.
Finish the sentence: The more the ray of light is slowed down….?
The more it is refracted.
What does it mean for an image to be ‘virtual’?
It cannot be formed on a screen.
The image seen in a plane mirror is laterally inverted. What does this mean?
The left appears as the right and ALWAYS UPRIGHT.
What is dispersion?
The breaking up of white light into a continuous spectrum of different colours when it is passed through a triangular prism.
Why does dispersion take place? What does this mean?
Different colours of light travel at different speeds in other transparent materials such as glass or Perspex. This means that different colours bend or refract by different amounts when they pass from air into glass.
Finish the sentence: The greater the change in speed…
The greater the amount of refraction.
