Lenses

Describe a convex/ converging lense

Have an outwards bulge in the centre which allows them to refract parallel rays of light inwards to a single point (principal focus )

Describe a diverging lense

They cave in on either side which causes them to refract parallel rays outwards. It causes the light to spread outwards.

When is a real image formed?

When light rays actually come together to form the image, e.g whenever you look at areal life object

When is a virtual image formed?

When the light rays don't come together where the image appears to be. Eg in a mirror

What is the principal focus?

A point where parallel incident rays meet after reflecting or refracting.

What is the focal length?

The distance between the optical centre of the lens and the screen.

What type of image does a concave lens form?

A virtual image

What type of image does a convex lens form?

A real image.