Question

At what distance should an object be placed from convex lens of focal length 9 cm to obtain an image at 18 cm from it ? What will be the magnification produced in this case ?​

Answer 1

Answer:

u = -18cm and magnification = -1

Explanation:

f = 9cm

v = 18cm

u = ?

1/f = 1/v - 1/u

1/9 = 1/18 - 1/u

1/9 - 1/18 = -1/u

(2 - 1)/ 18 = -1/u

1/18 = -1/u

u = -18cm

m = v/u

m = 18/-18

m = -1