This key facts covers Key Terms and the Magnification Equation 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 6 of 14 in this topic. Use this key facts to connect the idea to the wider topic before moving on to questions and flashcards.
🔑 Key Terms and the Magnification Equation
- Principal axis — the horizontal line through the centre of the lens
- Focal point (F) — where parallel rays converge (convex) or appear to diverge from (concave)
- Focal length (f) — distance from the lens centre to the focal point
- Magnification = image height ÷ object height
Quick Check: An object is 2 cm tall and its image through a lens is 6 cm tall. What is the magnification?
Magnification = image height ÷ object height = 6 ÷ 2 = 3. The image is 3 times larger than the object.
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.