Question

A convex lens of power 4D forms a real and inverted image three times the size of an object find the position of the object and image.

please help, I'm struggling with these numericals​

Answer 1

Answer:

v= 1m , u = -0.33 m

Explanation:

Given,

Power of the lens=> 4D=1/f

=>f = 1/4 = 0.25 m

Magnification => -3 = v/u

=> v = -3u

Now,

1/v-1/u = 1/f

=>1/(-3u) -1/u = 1÷1/4

=>(-1)/ 3u -1/u = 4

=> -1 -3/3u =4

=>-4/4=3u

=>u = -1/3

= -0.33 m (distance of object)

So, v = -3u = -3× -1/3

= 1 m (distance of image)