Question

Solve the numerical ​

Answer 1

Explanation:

Given,

In case of Concave lens,

Focal length,f = -10cm

Height of object, h = +2.5cm

Object Disatnce, u = -30cm

Image distance, v = ?

Height of the image, h'= ?

Using lens formula,

1/v - 1/u = 1/f

1/v = 1/f + 1/u

1/v = 1/-10 + 1/-30

1/v = -1/10 - 1 /30

1/v = - 3 + 1/30

1/v = -2/30

v = -30/2

v = -15 cm. ---------

So, Image is 15 cm behind the lens.

Now, magnification,m = v/u = h'/h

m=-15/-30= h'/2.5

m = 1/2= h'/ 2.5

m = h'= 2.5/2

h'= 1.25cm

So, Height of the object us diminished i.e,1.25cm