The magnification is 0.54
Given,
The distance between object and concave lens, u = -21 cm
Focal length of the concave lens, f = -25 cm
Let m be the magnification.
m = v/u
Here v is the position of image.
We have to find v first.
By using lens equation we can determine v.
That is,
1/f = 1/v – 1/u
So,
- (1/25) = 1/v – (-1/21)
- (1/25) = 1/v + 1/21
1/v = - (1/25) – 1/21
1/v = (-25 – 21) / (21 x 25)
1/v = - (46/525)
Therefore v = - (525/46)
v = -11.41 cm
Now we have to find magnification, m.
m = v/u
= (-11.41) / (-21)
= 0.54
Here magnification is 0.54
Learn more about concave lens here: brainly.com/question/12944945
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