Q50 of 62 Page 106

The focal length of a concave mirror is 30 cm, if an object is placed at a distance of 20 cm, calculate the position and nature of the image.

Given


Focal length of Concave mirror = -30cm (focal length of concave mirror is negative)


Distance of object from mirror = -20 cm (since object is on the left-hand side of lens and acc. To our sign convention)


Distance of image from mirror = ?


Formula Used


Mirror formula



Magnification formula



Using Mirror formula



V = 60 cm


Hence the image is at a distance of 60cm from mirror and is virtual.


Using magnification formula



M = 3


Hence, the image is 3 times the object and is erect.


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48

An object is placed 60 cm away from a convex lens of focal length 30 cm. If the height of the object is 3 cm then calculate the position and nature of the image.

 49

An object is placed 10 cm away from a convex lens. The focal length of the lens is 40 cm, calculate the position and nature of the image.

 51

The image of an object placed in front of a concave lens is formed at 10 cm. If the focal length of lens is 15cm then calculate distance of object from lens.

 52

Calculate the magnification of convex lens of focal length 10 cm when the image formed by lens is erect at the distance of nearest point of vision.