Lenses and Images Flashcards
How do lenses form images?
By refracting light and changing its direction.
What are the two types of lens?
Converging and diverging
What is a converging lens’ shape like? What does it cause rays of light to do?
It has a convex shape. It causes rays of light to converge( come together) at the principle focus.
What is a diverging lens’ shape like? What does it cause rays of light to do?
It is concave. It causes rays of light to diverge (spread out).
What is the principle focus of a converging lens?
Where rays hitting the lens, parallel to the axis meet.
What is the principle focus of a diverging lens?
Where rays hitting the lens, parallel to the axis appear to all come from. (You can trace them back)
What are the three golden rules when drawing ray diagrams?
1) A ray parallel to the axis is refracted through the focus.
2) A ray to the centre of the lens passes through undeflected.
3) A ray through the focus is reflected parallel to the axis.
What three things do you need to include to describe an image?
1) Whether it is larger or smaller( magnified or diminished)
2) Upright or laterally inverted
3) Real or virtual