Podcast
Questions and Answers
What happens to the rays of light after refracting through a convex lens?
What happens to the rays of light after refracting through a convex lens?
A concave lens always converges the rays of light after refraction.
A concave lens always converges the rays of light after refraction.
False
What is the central part of a lens similar to?
What is the central part of a lens similar to?
A rectangular glass slab
The radius of a sphere whose surface forms a part of a lens is called the ______________________.
The radius of a sphere whose surface forms a part of a lens is called the ______________________.
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Match the following terms related to lenses with their definitions:
Match the following terms related to lenses with their definitions:
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A concave lens is always thicker in the middle and thinner at the edge.
A concave lens is always thicker in the middle and thinner at the edge.
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What is the function of a lens in optical instruments?
What is the function of a lens in optical instruments?
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What is the name of the lens that is thick in the middle and thin at the edge?
What is the name of the lens that is thick in the middle and thin at the edge?
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A lens can be assumed to be made by the combination of many ______________ in correct order.
A lens can be assumed to be made by the combination of many ______________ in correct order.
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Match the following types of lenses with their characteristics:
Match the following types of lenses with their characteristics:
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Study Notes
Lenses and Their Characteristics
- A lens is an optical device made up of a transparent medium bounded by spherical surfaces, typically made of glass or plastic.
- Lenses are of two types: convex lens and concave lens.
Convex Lens
- A convex lens is thick in the middle and thin at the edge.
- When parallel rays of light fall on a convex lens, they converge at a point after refraction.
- A convex lens is also called a converging lens.
- Examples of convex lenses include biconvex lens, planoconvex lens, and concavo-convex lens.
- The human eye contains a natural convex lens.
Concave Lens
- A concave lens is thin in the middle and thick at the edge.
- When parallel rays of light fall on a concave lens, they diverge after refraction, appearing to diverge from a point.
- A concave lens is also called a diverging lens.
- Examples of concave lenses include biconcave lens, planoconcave lens, and convexo-concave lens.
Lens as a Group of Prisms
- A lens can be assumed to be made up of a combination of many prisms in correct order.
- A convex lens consists of prisms in the upper half with their bases inward and prisms in the lower half with their bases outward.
- The parts of the lens bend the incident light, with the central part acting like a rectangular glass slab, allowing light to travel straight through.
- A concave lens can also be considered as composed of the combination of prisms, but with the bases of prisms opposite to those of a convex lens.
Terminology Related to Lenses
- Centre of curvature refers to the center of the sphere of which the lens is a part.
- Radius of curvature refers to the radius of the sphere whose surface forms a part of a lens.
- Principal axis refers to the imaginary line that joins the two centers of curvature.
- Focal length is the distance between the center of curvature and the point where parallel rays of light converge or diverge after refraction.
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Description
Learn about the importance of lenses in camera, spectacles, microscope, telescope and human eye. Discover how lenses help in clear visibility of objects and form images on the retina.
