Question

According to mirror formula, the correct relation between the image distance $\left(v\right)$, object distance $\left(u\right)$ and the focal length $\left(f\right)$ is:

• A. $\frac{1}{v}+\frac{1}{u}=\frac{1}{f}$
• B. $\frac{1}{v}+\frac{1}{f}=\frac{1}{u}$
• C. $\frac{1}{v}+\frac{1}{u}=-\frac{1}{f}$
• D. $\frac{1}{v}+\frac{1}{f}=-\frac{1}{u}$

Answer 1

The correct option is A $\frac{1}{v}+\frac{1}{u}=\frac{1}{f}$

According to mirror formula,
$\frac{1}{v}+\frac{1}{u}=\frac{1}{f}$
where:
$u:$ Object distance
$v:$ Image distance
$f:$ Focal length

When using this formula, all values should be used with proper signs as per the new cartesian sign convention.