Question

You wish to create a real image with a magnification of −16 (that is an inverted image).

If you have a lens with a focal length of 15 cm, how far away should you place the object? (to 2 s.f and in cm)

Answer 1

Answer:-

magnification = -16

focal length = 15cm

$m=\frac{v}{u}$

$-16=\frac{v}{u}\\ v=-16u$

According to lens formula

$\frac{1}{v}-\frac{1}{u}=\frac{1}{f}$

$\frac{1}{-16u}-\frac{1}{u}=\frac{1}{f}\\ \frac{-1-16}{16u}=\frac{1}{15}$

$u=-16 \ cm$

hence object distance is , u= 16 cm

[negative sign indicates that object is in-front of the lens ]