Answer
(a) $0.286$
(b) $0.082$
Work Step by Step
(a) We know that
$m=\frac{-f}{d_{\circ}-f}$
We plug in the known values to obtain:
$m=-\frac{-30.0cm}{75.0cm+30.0cm}=0286$
(b) We know that
$d_{i2}=\frac{fd_{\circ2}}{d_{\circ1}-f}$
We plug in the known values to obtain:
$d_{i2}=\frac{(-30.0cm)(74cm)}{74cm+30.0cm}=-21.34cm$
and $d_{i1}=\frac{fd_{\circ1}}{d_{\circ1}-f}$
$d_{i1}=\frac{(-30.0cm)(76.0cm)}{76.0cm+30.0cm}$
$d_{i1}=-21.50cm$
The length of the image is:
$L_i=d_i2-d_i=-21.34-(-21.50)=0.16cm$
Now, $m=\frac{Li}{L_{\circ}}$
$m=\frac{0.16cm}{2.00cm}=0.082$
