If the power of a lens is -4.0 D, then it means that the lens is a ______. - Science

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MCQ
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If the power of a lens is -4.0 D, then it means that the lens is a ______.

Options

  • concave lens of focal length -50m

  • convex lens of focal length +50cm

  • concave lens of focal length -25cm

  • convex lens of focal length -25m

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Solution

If the power of a lens is -4.0 D, then it means that the lens is a concave lens of focal length -25cm.

Explanation:-

P = -4 D

`P=100/(f(cm))`

`f(cm)=100/P`

`100/-4=-25"cm"`

Negative focal length means concave lens. Concave lens of focal length -25cm.

Concept: Concave Lens
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