Question

Please answer question 2​

Answer 1

h = object height

h' = image height

u = object distance

v = image distance

f = focal length

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Solution:

Here, h = 3cm

u = -10cm

Now, since image is virtual (and erect) magnification will be positive.

So h' will be positive

h' = 12cm

By magnification formula,

m = h'/h = -v/u

12/3 = -v/-10

4 = v/10

v = 40cm

So, distance of image will be 40 cm

Now, by lens formula

1/f = 1/v - 1/u

1/f = 1/40 - 1/10

1/f = -3/40

f = -40/3 = -13.33cm