What this lesson teaches
Refraction and lens formula.
Science in Action
Can you finish convex lens focal length in about 35 min?
Convex Lens Focal Length
You will refraction and lens formula.
Duration35 min
Age GroupAges 14–16
DifficultyAdvanced
SubjectScience
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What you need
How the activity runs
The learning connection
Finding the focal point of a physical lens through direct observation makes the concept of focal length personally anchored rather than textbook-defined. Students who locate a focal point themselves can apply the concept to eyeglasses, cameras, and telescopes without being told — they already know what focal length means.
Try it with your learner
1. Set up lens between candle and screen. 2. Adjust for sharp image. 3. Measure distances. 4. Calculate f.