What is the incident ray?
The incoming ray of light
What is the reflected/refracted ray?
The outgoing ray of light
What is the normal?
A line drawn at a right angle to the reflective/transparent surface
What is the angle of incidence?
The angle between the incident ray and the normal
What is the angle of reflection/refraction?
The angle between the reflected/refracted ray and the normal
What are the two laws of reflection?
- The angle of incidence is equal to the angle of reflection
- The incident ray, the reflected ray and the normal all lie in the same plane
How do images appear in a plane mirror?
Laterally inverted (flipped)
What is a real image?
An image formed by rays of light focusing (converging) to a single point and being projected onto a surface
What is a virtual image?
An image formed by extrapolated rays of light that are not formed physically by rays. It cannot be formed on a screen.
What are the rules for the size and position of an image in a mirror?
- Image the same size as object
- Image same distance from mirror as object
- A line joining the object and image would pass through the mirror at a right angle
What is refraction?
The bending of light as it travels at a different speed through a different medium
If the transparent material has parallel sides, how does the light emerge?
Parallel to its original direction
If the transparent material does not have parallel sides, how does the light emerge?
Deviated (different to its original direction)
How do you define the refractive index of a material?
- speed of light in a vaccum / speed of light in the medium
OR - sin (angle of incidence) / sin (angle of refraction)
What happens to white light when it refracts through a prism?
It disperses into a spectrum
What is total internal reflection?
When light hits the inside of a transparent material at an angle greater than the critical angle, and is internally reflected entierly
What happens if a light ray hits the inside of a transparent material at an angle lesser than the critical angle?
The ray splits into a refracted ray and a weaker reflected ray
What happens if a light ray hits the inside of a transparent material at the critical angle?
The ray splits, but the refracted ray only just leaves the surface
What happens if a light ray hits the inside of a transparent material at an angle greater than the critical angle?
There is no refracted ray - the inside of the transparent material acts like a perfect mirror
What are the properties of a convex (converging) lens?
- Thicker in the middle, thinner at the edges
- Rays parallel to the principle axis are bent inwards when they pass through it
- Principle focus is where the rays converge
What are the properties of a concave (diverging) lens?
- Thinner in the middle, thicker at the edges
- Rays parallel to the principle axis are bent outwards
- Principle focus is where the rays appear to diverge from if extrapolated
What is the principle axis?
The ray of light that passes through the centre of a lens at a 90 degree angle
What is focal length?
The distance between the centre of a lens and the principle focus
What are the properties of a real image formed by a convex lens?
- Inverted (upside-down)
- Diminished (smaller than object) if object is far away
- Enlarged (larger than object) the closer the object gets
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History Module 218
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Physics Module 244
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Economics Module 361
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Economics Module 423
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Physics Module 519
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Psychology Module 119
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Economics Module 515
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Psychology Module 219
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Psychology Module 348
