Car drivers must be able to - read a speedometer from a distance of 50 cm - read a number plate from a distance of 20.5 m - AQA - A-Level Physics - Question 1 - 2019 - Paper 5

In Figure 1, without corrective lens, the rays of light from the number plate converge and form an image in front of the retina, making it difficult for the driver to see the object clearly.

In Figure 2, with a corrective lens, we should draw a concave lens to diverge the rays of light before they enter the eye. This adjustment helps to project the image on the retina at the correct position, allowing the driver to see the number plate clearly.

1. Draw the dotted lines from the edges of the number plate to the concave lens, showing the incoming rays.
2. Indicate how the rays diverge after passing through the lens.
3. Mark the location where the image is formed on the retina.

To determine the suitable lens, we need to find the power of each lens and understand which one correctly corrects the driver's vision. The formula for lens power (P) is given by:

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

where f is the focal length in meters.

1. Lens A:

   Power of A = -2.1 D

   Focal length (f) = -\frac{1}{2.1} = -0.476 m (suitable to correct vision)

2. Lens B:

   Power of B = -1.77 D

   Focal length (f) = -\frac{1}{1.77} = -0.565 m (also suitable)

3. Lens C:

   Power of C = +1.95 D (not suitable for myopia)

Since lens A and lens B are both suitable for the correction of myopia, we would select lens B as it has the least refractive power, which would provide adequate correction for the driver's distance vision.