A lens is a piece of transparent material with two refracting surfaces such that at least one is curved and the material of lens is different from that of the surroundings.
A thin spherical lens which is thicker at the middle than the edges behaves as a convergent or convex lens i.e. it converges parallel rays. Depending on the type of two surfaces they can be further classified as:
1. Double Convex Lens: When both the refracting surfaces are convex surfaces. It is called double convex lens.
2. Plano - Convex Lens: When one of the refracting surface is plane and the other refracting surfaces is convex surfaces. It is called plano - convex lens.
3. Concavo Convex Lens: When one of the refracting surface is a concave surface and the other refracting surfaces is convex surfaces. It is called concavo convex lens.
If the central portion of a lens is thinner than marginal, it diverges parallel rays and behaves as a divergent or a concave lens.
1. Double Concave Lens: When both the refracting surfaces are concave surfaces. It is called double concave lens.
2. Plano - Concave Lens: When one of the refracting surface is plane and the other refracting surfaces is concave surfaces. It is called plano - concave lens.
3. Convexo Concave Lens: When one of the refracting surface is a concave surface and the other refracting surfaces is convex surfaces. It is called convexo concave lens.
Which of the following are correct ? (a) A thin spherical lens which is thicker at the middle than the edges behaves as a divergent lens. (b) When one of the refracting surface of a lens is plane and the other refracting surfaces is concave surfaces. It is called plano - concave lens. | |||
Right Option : B | |||
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When both the refracting surfaces are concave surfaces. It is called _________________ . | |||
Right Option : C | |||
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A convex lens is ____________________ . | |||
Right Option : B | |||
View Explanation |
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