Find the power of a lens with a focal length of 90mm (giving your answer to the nearest whole number).
Question
Find the power of a lens with a focal length of 90mm (giving your answer to the nearest whole number).
Solution
The power of a lens is given by the formula:
Power (P) = 1 / Focal length (f)
The focal length should be in meters for this formula. So first, convert the focal length from mm to meters:
90 mm = 0.09 m
Now, substitute the focal length into the formula:
P = 1 / 0.09
Calculate the above expression to find the power. The result is approximately 11.11.
Rounding to the nearest whole number, the power of the lens is 11 diopters.
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