Question

The lens equation is 1f=1p+1q, where f is the focal length of the lens, p is the distance of the object from the lens, and q is the distance of the image from the lens. The formula to find q is

Answer 1

I will assume its as I suggested
Then rearranging:-

1/q = 1/f - 1/p

Answer 2

Answer:

The required formula is $q=\frac{fp}{p-f}$.

Step-by-step explanation:

The given equation is

$\frac{1}{f}=\frac{1}{p}+\frac{1}{q}$

where,

1. f is the focal length of the lens.

2. p is the distance of the object from the lens.

3. q is the distance of the image from the lens.

We have to rearrange the formula for q.

Multiply both sides by fpq.

$\frac{fpq}{f}=fpq(\frac{1}{p}+\frac{1}{q})$

$pq=\frac{fpq}{p}+\frac{fpq}{q}$

$pq=fq+fp$

Subtract fq from both the sides.

$pq-fq=fp$

Take out the common factor q.

$q(p-f)=fp$

Divide both the sides by (p-f)

$q=\frac{fp}{p-f}$

Therefore the required formula is $q=\frac{fp}{p-f}$.