Question

Why convex lens has a positive power

Answer 1

The power of a convex lens is positive as a convex lens has a positive focal length, while the power of a concave lens is negative as concave lens has a negative focal length.

It is because focal length of convex lens is +ve and. Since P=1/f. Therefore power of convex lens is positive.

Answer 2

When we use different lenses and power is calculated, then in case of lens that is convex is always said to be positive, this happens because the focal length of the convex lenses is mostly positive.

Explanation:

• But when lenses that are concave shaped then the focal length is in negative side of the lens. Hence, it will show a power that is negative in polarity.
• Power is is seen as the reciprocal or one upon of the focal length.
• Hence when the power is considered for a convex lens the power will be positive because the focal length is positive.

To know more:

Why is the power of convex lens positive and that of a concave lens negative

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