| English | Converging lens |
|---|---|
| Bahasa Melayu | Kanta menumpu |
| 中文 | 凸透镜 |
Definition
A lens that is thicker at the centre and brings parallel rays of light together at a focal point.
In exam terms
A converging lens (convex lens) is thicker at the centre than at the edges and brings parallel rays of light together at a single focal point after refraction. Because it collects rays to a point, it is also called a positive lens.
The distance from the optical centre to the focal point is the focal length f, measured in metres (m). A correct sentence: parallel rays passing through a converging lens meet at the principal focus. Depending on the object distance it can form a real, inverted image or a magnified virtual image (as in a magnifying glass).
Do not confuse it with a diverging lens
Do not confuse a converging lens with a diverging (concave) lens, which is thinner at the centre and spreads parallel rays apart so they appear to come from a focal point behind the lens. A diverging lens always forms a small, upright, virtual image.
In Paper 2, a ray diagram question expects you to draw at least two standard rays through a converging lens and locate the image, while a state one use question accepts answers such as a camera, projector or magnifying glass.
Source: DSKP KSSM Physics Form 4 and 5 (Versi English) (Bahagian Pembangunan Kurikulum (BPK), KPM)