Question

What is the average size of pupils in dim and bright lighting conditions?

A) Pupils are smaller in dim light and larger in bright light
B) Pupils are larger in dim light and smaller in bright light
C) Pupils remain constant in size regardless of lighting conditions
D) Pupil size varies randomly in different lighting conditions

Answer 1

Pupils are larger in dim light to allow more light into the eye and smaller in bright light to limit light intake. The pupil's diameter typically ranges from 3 mm in bright light to 7 mm in dim light, and the pupil can allow up to about 5.44 times more light in at its larger size.

Step-by-step explanation:

The average size of pupils in different lighting conditions changes because the iris adjusts the size to regulate the amount of light entering the eye. The correct answer to the question is B) Pupils are larger in dim light and smaller in bright light. In bright lighting conditions, such as broad daylight, the size of your pupil typically contracts to about 3 mm in diameter. Conversely, in dark situations or dim light, the pupil expands to accommodate more light, growing to about 7 mm in diameter.

To quantify how much more light the pupil can gather when it is 7 mm in diameter compared to when it is 3 mm, we can consider the area of a circle (since the pupil is approximately circular). The area of a circle is given by the formula A = πr², where r is the radius of the circle. This means that when your pupils dilate from 3 mm to 7 mm, they can allow up to approximately 5.44 times more light into the eye because the area of the pupil increases with the square of the radius.