Question

find the distanc of the image when an object is placed on the principal axis at a distance of 10cm in front of a concave mirror whose radius of curvature is 8cm

Answer 1

Answer :
$d_{i} = 6.67$

Explanation :

Mirror Equation  
$\frac{1}{f}=\frac{1}{d_{o}} + \frac{1}{d_{i}}$
                          $d_{o} = object distance = 10cm$
                          $d_{i} = image distance$
                          $f = focal length$

we know , for a mirror $f = \frac{r}{2}$
                          $r = radius of curvature$

since
$r = 8cm$
$f = 4cm$

substitutin in mirror equation
$\frac{1}{4} = \frac{1}{10} + \frac{1}{d_{i}}$
$\frac{1}{4} - \frac{1}{10} = \frac{1}{d_{i}}$
$\frac{5-2}{20} = \frac{1}{d_{i}}$
$d_{i} = \frac{20}{3}$
$d_{i} = 6.67$