What are the two types of lens?
Converging
Diverging
What is another name for a converging lens?
Convex
What is another name for a diverging lens?
Concave
What is a converging lens?
A lens that causes parallel rays to converge at a focal point
What is a diverging lens?
A lens that causes parallel rays to diverge as though they have come from a single point
What is a focal length?
The distance between the centre of a lens to the principal focus
Write the equation that links image height, magnification and object height
Magnification = (image height)/(object height)
What is the unit of magnification?
It has no unit as it is a ratio
A 2cm insect is viewed with a magnifying glass and appears to be 6 cm long. What is the magnification?
x2
Draw two symbols that may be used to represent a convex lens
Draw two symbols that may be used to represent a concave lens
What are the three rules for convex lenses?
An incident ray travelling parallel to the axis refracts through the lens and passes through the principal focus on the other side
An incident ray passing through the centre of the lens carries on in the same direction
An incident ray passing through the
What are the three rules for concave lenses?
An incident ray travelling parallel to the axis refracts through the lens and travels as though it has come from the principal focus.
An incident ray passing through the centre of the lens carries on in the same direction
An incident ray passing through t
What should you do if the refracted rays do not cross on the far side of the lens?
Track them back as virtual (dotted) rays
Where does the image occur on a ray diagram?
Where the rays cross
What three features of images should be used to describe them?
Orientation (Upright or inverted), Size (Magnified, diminished or the same size) and whether they are Real or Virtual