Chapter 18, Problem 63A

To determine

The image distance from the lens.

Answer to Problem 63A

  $39.33\text{cm}$ to the right of the lens

Explanation of Solution

Given:

The focal length of the convex lens, $f=25.5\text{cm}$

The object distance from the lens, $d_o=72.5\text{cm}$

Formula used:

Thin lens equation,

  $\frac{1}{f}=\frac{1}{d_i}+\frac{1}{d_o}$

Where,

  $\begin{array}{l}f=\text{focal length of the lens}\\ d_i=\text{ image distance}\\ d_o=\text{object distance}\end{array}$

Calculation:

Using the given values in Thin lens equation, the image distance will be,

  $\begin{array}{c}\frac{1}{f}=\frac{1}{d_i}+\frac{1}{d_o}\\ \frac{1}{25.5}=\frac{1}{d_i}+\frac{1}{72.5}\\ d_i=\frac{72.5\times 25.5}{72.5-25.5}\\ =39.33\text{cm}\end{array}$

Conclusion:

Hence, the image is formed at a distance of $39.33\text{cm}$ to the right of the lens.