Assessment: Lenses
Answer every question, then submit to see your score and which topics to review.
Part A — Concept Questions
Why can a curved surface focus parallel light rays to a point, unlike a flat surface?
MediumWhat does a NEGATIVE magnification value indicate about the image?
MediumWhy do opticians use dioptres (power) rather than focal length when prescribing lenses?
EasyPart B — Formula & Application
An object is placed at u = -25 cm from a lens with f = 5 cm. Find the image distance v.
MediumFind the power of a lens with focal length 0.2 m.
MediumPart C — Problem Solving
A lens forms an image at v = 12 cm from an object at u = -4 cm. Find the magnification.
HardA lens forms a real image at v = 30 cm when the object is at u = -60 cm. Find the focal length f.
HardPart D — Real-Life Application
How does a camera's autofocus system relate to the lens equation?
MediumWhy does holding a magnifying glass close to small text make the text look bigger?
MediumPart E — Challenge
Two thin lenses with powers +3 D and -1 D are placed close together. What is the combined power?
Hard0/10 answered