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 a lens, we use the formula:

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

Where:

• P is the power of the lens in diopters (D)
• f is the focal length in meters.

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

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

Now substituting the value into the formula:

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