Quick Answer:The Concave Lens is a 50 mm diameter bi-concave (diverging) lens with ground and polished edges, used on an optical bench to study light divergence, virtual images and focal length, and to show how short sight is corrected.
Last updated: 18 October 2026
Key Features
Bi-concave lens, thinner at the centre than at the edges.
50 mm diameter to suit standard lens holders.
Ground and polished edges.
Surface quality scratch-dig 60/40 or better.
Technical Specifications
Specification
Value
Type
Bi-concave (diverging)
Diameter
50 mm
Edges
Ground and polished
Surface quality
Scratch-dig 60/40 or better
Mounting
Standard 50 mm lens holders and optical benches
How It Is Used
Mounted in a 50 mm holder on an optical bench, the lens spreads a beam of light so that it appears to come from a virtual focus on the same side as the source. Students use it to find focal length and to show how a diverging lens corrects myopia (short sight).
Frequently Asked Questions
What diameter is the Concave Lens?
50 mm, to fit standard 50 mm lens holders and optical benches.
