GCSE Physics: Reflection and Refraction.

When light hits a surface, it changes direction.

THIS IS CALLED REFLECTION.

The normal line is perpendicular to the reflecting surface at the point of incidence.

The normal line is used to calculate the angles of incidence and reflection...

ANGLE OF REFLECTION = ANGLE OF INCIDENCE i = r

PLANE MIRRORS
The image in a plane mirror is:

• the same size as the object
• upright and virtual
• the same distance behind the mirror as the object in front.

When light crosses an interface (a boundary between two densities) it changes direction.

Unless, it meets the boundary at 90 degrees.

THIS IS CALLED REFRACTION

A triangular prism doesn't have any parallel sides, so a light ray travelling through it is deviated (changes direction).

If the speed is REDUCED, refraction is TOWARDS the normal.
If the speed is INCREASED, refraction is AWAY FROM the normal.

The difference between Normal and Virtual Images is very easy to understand.

You need to ensure that you are perfectly clear on the difference.

REAL Can be formed on a screen.
The rays of light that form the image, actually pass through it.

VIRTUAL Cannot be formed on a screen.
The rays that form the image, only appear to pass through it.

The names of the two images basically say it all. Real is normal and virtual is imaginary in a way - the rays do not really pass through the image, the only appear to.

• What size is the image in a plane mirror? 1
• What is reflection? 2
• What is the angle of reflection equal to? 1
• What is refraction? 2
• What happens in refraction, if the speed is reduced? 1
• What happens in refraction if the speed is decreased? 1

The answers are all within the previous flashcards. Look for the answers yourself, this will greatly help you. It is much more beneficial than simply ticking or crossing.

9 - A*
8 - A
6 - 7 - B
4 - 5 - C
3 and below - C