This definitions covers Key Definitions within Lenses & Images for GCSE Physics. Revise Lenses & Images in Waves for GCSE Physics with 13 exam-style questions and 15 flashcards. This topic appears less often, but it can still be a useful differentiator on mixed-topic papers. It is section 8 of 14 in this topic. Make sure you can use the exact wording confidently, because definition marks are often lost through vague language.
📖 Key Definitions
Convex (converging) lens: A lens that is thicker in the middle, which refracts parallel rays to converge at the focal point.
Concave (diverging) lens: A lens that is thinner in the middle, which refracts parallel rays to diverge, appearing to originate from the focal point on the same side.
Focal length: The distance from the centre of the lens to the focal point, measured in metres.
Real image: An image formed where light rays actually converge; can be projected onto a screen; always inverted.
Virtual image: An image formed where light rays appear to diverge from; cannot be projected onto a screen; always upright.
Magnification: The ratio of image height to object height; magnification = image height ÷ object height (no units).
Practice questions for Lenses & Images
What does a convex (converging) lens do to parallel rays of light?
Explain the difference between a converging lens and a diverging lens. Include what each type does to parallel rays of light.