Chapter 25, Problem 16P

To determine

(a) To determine:

The focal length of the eye lens system when object is at 34 cm from eyes

Answer to Problem 16P

Solution:

$2\text{cm}$

Explanation of Solution

Given:

$\text{Image distance}=v=\text{2cm}$

Formula used:

$\frac{1}{f}=\frac{1}{u}+\frac{1}{v}$

Calculation:

When object is at infinity.

According to lens equation’

$\begin{array}{l}\frac{1}{f}=\frac{1}{u}+\frac{1}{v}\\ \frac{1}{f}=\frac{1}{\infty }+\frac{1}{0.02}\\ \frac{1}{f}=0+50\\ f=0.02\text{m}\\ f=2\text{cm}\end{array}$

To determine

(b) To determine:

The focal length of the eye lens system when object is at 34 cm from eyes

Answer to Problem 16P

Solution:

$1.88\text{cm}$

Explanation of Solution

Calculation:

When object is at 34cm.

According to lens equation’

$\begin{array}{l}\frac{1}{f}=\frac{1}{u}+\frac{1}{v}\\ \frac{1}{f}=\frac{1}{0.34}+\frac{1}{0.02}\\ \frac{1}{f}=2.94+50=52.94\\ f=0.0188\text{m}\\ f=1.88\text{cm}\end{array}$