rules for converging

Question 1

mirror

Answer 1

1. a light ray parallel to the principal axis is reflected through the ficus. This is how the focus is defined.
2. a ray through (F) will reelect parallel to the principal axis
3. a ray aimed at the vertex will follow the law of reflection

Question 2

lenses

Answer 2

1. A ray parallel to the principal axis is refracted through the principal focus, (F)
2. A ray through the secondary principal focus, (F’), is refracted parallel to the principal axis.
3. A ray through the optical centre, (O), continues straight through without being refracted.