Question

A Convex Lens Has A Focal Length Of 15cm At What Distance Should The Object From The Lens Be Placed,So That It Forms An Image at 10 cm From The Lens. Find The Magnification Produced By The Lens​

Answer 1

Answer:

v =10 cm

f = 15 cm

lens formula

$\frac{1}{f} = \frac{1}{v} - \frac{1}{u} \\ \frac{1}{15} = \frac{1}{10} - \frac{1}{u} \\ \frac{1}{15} - \frac{1}{10} = - \frac{1}{u} \\ \frac{2 + 3}{30} = - \frac{1}{u} \\ \frac{5}{30} = - u \\ u = - 6 \: cm \:$

so object distance is -6cm

magnification = v /u. = 15 / -6 = 5 /-2. = -2.5