How much must the focal length of an eye change when an object,originally at 4.00 m,is brought to 40.0 cm from the eye?
A)0.13 cm
B)2.48 cm
C)2.35 cm
D)2.50 cm
E)0.19 cm

Question

Quizplus · Accepted Answer

The correct answer is A because the change in focal length is given by the formula:$$\Delta f = \frac{1}{d_o} - \frac{1}{d_i}$$where $d_o$ is the original object distance and $d_i$ is the new object distance. Plugging in the values given in the question, we get:$$\Delta f = \frac{1}{4.00 m} - \frac{1}{0.400 m} = 0.13 cm$$

How Much Must the Focal Length of an Eye Change