The focal length of a lens is +150mm. What kind of lens is it and what is its power?
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$\text{f}=+150\text{mm}=+0.15\text{m}$It is a convex lens since its focal length is positive.
$\text{P}=\frac{1}{\text{f}}=\frac{1}{0.15}=+6.66\text{D}$
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