What is the relationship between the angle of incidence and the angle of reflection?
- By looking at my angles for each light ray, the relationship is the angle of incidence = angle of reflection
- This is called the law of reflection
Why does light change direction when moving through a medium?
- When light moves from one medium to another, it will change direction because it changes speed
What happens when light slows down?
- When light slows down, it refracts towards the normal
What happens when light speeds up?
- When light speeds up, it refracts away from the normal
What is snell’s law for refraction?
n = sin i/sin r
Has no units
Only works when light is slowing sown so from air/vacuum into a medium
When can total internal reflection happen?
Total internal reflection can only happen if:
- a ray hits a boundary where it would be speeding up if the angle of incidence is bigger than the critical angle
- eg. glass -> air critical angle = 42
What is the equation for critical angle?
sinc = 1/n
When do you get a critical angle?
- Only get a critical angle if it’s speeding up glass -> air
What are some uses of TIR?
- Fibre optic cables
- (prism in a) periscope
- endoscope
How are images formed?
- Images are formed where rays meet
How does a virtual image occur?
- A virtual image occurs where rays appear to meet but do not actually meet
What is refraction?
- When light moves from one medium to another it will change direction because it changes speed
