Question

An object is 25 cm in front of a diverging lens with magnitude focal length 18 cm. Determine the position in cm of the image with respect to the lens assuming the object distance is positive.

Answer 1

object distance (o) = 25 cm

focal length (f) = 18 cm

Lens equation is given as

1/f = 1/o + 1/i

where i is image distance

for diverging lens, f is negative

so,

1/i = 1/f - 1/o

1/i = 1/-18 - 1/25

i = -10.465 cm

negative sign tells us that the image is virtual.

so,

image position = 10.465 cm