Light: Mirrors and Lenses
Looking through the two lenses
Look through two kinds of lenses and see how each one changes what you see.
Activity 10.9. You need a convex lens, a concave lens, a lens holder and a small object.
Stand the convex lens upright in its holder and put the object behind it (raise it if needed so it's level with the lens). Look at the object through the lens from the other side. Then slowly move the object farther away, watching all the time. Repeat with the concave lens.
| Lens | Object close | Object far |
|---|---|---|
| convex | erect and enlarged | inverted: at first enlarged, then smaller |
| concave | always erect and diminished | still erect, and smaller as it moves away |
A concave lens never turns the object upside down and never makes it look bigger.
Compare these with the mirrors in Activity 10.3:
- a convex lens behaves like a concave mirror (erect and enlarged close up, inverted far away);
- a concave lens behaves like a convex mirror (always erect, always smaller).
The names run the opposite way round, so it's worth remembering this pairing.
Look at your own recorded observations and draw your own conclusions before you read anyone else's.
Practise this lesson
Questions that get harder as you improve, a Tutor that helps without giving the answer away, and progress you can see. Free for every learner.
No account, no email address. Opens the real product.