A coin collector looks at the detail of a pound coin through a converging lens (magnifying glass) - Edexcel - GCSE Physics - Question 1 - 2017 - Paper 1

To calculate the power of the lens, we use the formula:

$P = \frac{1}{f}$

where:

• $P$ is the power in diopters (D)
• $f$ is the focal length in meters

First, we must convert the focal length from centimeters to meters:

$f = 10 \text{ cm} = 0.1 \text{ m}$

Now, we can substitute the value into the power formula:

$P = \frac{1}{0.1} = 10 \text{ D}$

Therefore, the power of the lens is 10 D.