An object is placed perpendicular to the principal axis of a convex lens of focal length 10 cm

An object is placed perpendicular to the principal axis of a convex lens of focal length 10 cm. The distance of the object from the lens is 15 cm. Find nature and position of image.

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Focal length f = 10 cm

Object distance u = -15 cm

Image distance v= ?

The lens formula is 1/f = 1/v - 1/u
1/v = 1/u + 1/f
1/v = 1/-15 + 1/10
1/v = -2+3/30
1/v = 1/30 or v = 30
The positive sign of v shows that the image is formed at a distance of 30 cm on the other side of optical centre. The image is real and inverted.

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