Question

The lens equation is 1/f=1/p+1/q , 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:
a. q=pf/p-f
b. q=p-f/pf
c. q=pf/p+f

Answer 1

Answer:

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

Step-by-step explanation:

The lens equation is $\frac{1}{f}=\frac{1}{p}+\frac{1}{q}$.

To solve this formula for $q$, we need to multiply each term by $fpq$.

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

We cancel out the common factors to get;

$pq=fq+fp$.

We group the terms in q on one side of the equation;

$pq-fq=fp$.

Factor q.

$q(p-f)=fp$.

Divide both sides by $(p-f)$

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

The correct answer is A

Answer 2

1/f=1/p + 1/q
least comom multiple=pfq
(pq)/(pfq)=(fq)/(pfq)+(pf)/(pfq)
Because all denominators are the same, we can eliminate the denominators.
pq=fq+pf
pq-fq=pf
q(p-f)=pf
q=pf / (p-f)

Answer: a. q=pf / (p-f)