## Book: HC Verma - Concepts of Physics Part 1

### Chapter: 18. Geometrical Optics

#### Subject: Physics - Class 11th

##### Q. No. 52 of Exercises

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52
##### A convex lens has a focal length of 10 cm. find the location and nature of the image if a point object is placed on the principal axis at a distance of (a) 9.8 cm, (b) 10.2 cm from the lens.

the focal length of the lens is given as f= 10 cm.

(a) when the object is at distance 9.5 cm away from the lens, i.e.

u=-9.5cm

Using lens formula,

Magnification m= v/u =-490/-9.8 = 50cm

Hence, image is virtual and erect.

(b) when the object is at distance 9.5 cm away from the lens, i.e. u=-10.2 cm

Using lens formula,

Magnification m= v/u = 510/-9.8 = -52.04 cm

Hence, image is real and inverted.

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