lenses- drawing ray diagrams.

Question 1

how do we represent a diverging lens?

Answer 1

line with two arrows pointing inwards.

Question 2

how do we present a converging lens?

Answer 2

line with two arrows pointing outwards.

Question 3

what is the principle axis?

Answer 3

imaginary line through the middle of the lens.

Question 4

what is the formula for magnification?

Answer 4

magnification= image height/ object height.

Question 5

what kind of number is the magnification and why does it not have units?

Answer 5

positive number.
ratio.

Question 6

what are the rules for a ray diagram?

Answer 6

any ray parallel to the principle axis is refracted through the focal point.
rays passing through the centre of the lens go straight through.
rays that pass through the focal point are refracted and emerge parallel to the principle axis.

Question 7

what are the different ways of describing an image?

Answer 7

upright or inverted (upside down compared to the object.)
magnified or diminished.
real or imaginary.

Question 8

how can you tell if the image is real or imaginary?

Answer 8

real:
is the image formed where the light rays are focussed.
can be projected on to a screen.
virtual:
is the image formed where the mathematical extensions of the light rays are focussed.
cannot be projected on to a screen.