# Problem: Anna holds an 11 D magnifier directly in front of her eye to get a close look at a 19-mm -diameter penny. Assume a typical 25 cm near point and a distance of 1.7 cm between the lens and the retina.(a) What is the closest possible distance that she can hold the coin to have it appear in focus?(b) At this distance, how large does the image of the coin appear on her retina?Express your answer with the appropriate units.

###### FREE Expert Solution

Lens maker equation, for the eye:

$\overline{)\frac{\mathbf{1}}{{\mathbf{s}}_{\mathbf{o}}}{\mathbf{+}}\frac{\mathbf{1}}{{\mathbf{s}}_{\mathbf{i}}}{\mathbf{=}}\frac{\mathbf{1}}{\mathbf{f}}}$

(a) For equivalent focal length:

1/Fe = 1/f + P (where P is the power of the lens)

1/Fe = 1/1.7 + 1/25 + 11/100 = 251/340

Considering:

###### Problem Details

Anna holds an 11 D magnifier directly in front of her eye to get a close look at a 19-mm -diameter penny. Assume a typical 25 cm near point and a distance of 1.7 cm between the lens and the retina.

(a) What is the closest possible distance that she can hold the coin to have it appear in focus?

(b) At this distance, how large does the image of the coin appear on her retina?