A convex lens forms a real and inverted image of a needle at a distance of 50 cm from it. Where is the needle placed in front of the convex lens if the image is equal to the size of the object? Also, find the power of the lens.

Asked by Vishal kumar | 1 year ago |  180

1 Answer

Solution :-

The position of image should be at 2F, since the image is real and same size.

It is given that the image of the needle is formed at a distance of 50 cm from the convex lens. Therefore, the needle is placed in front of the lens at a distance of 50 cm.

Object distance (u) = - 50 cm

Image distance, (v) = 50 cm

Focal length = f

According to the lens formula.

\( \frac{1}{u}-\frac{1}{u}=\frac{1}{f}\)

\( \frac{1}{f}=\frac{1}{50}-\frac{1}{-50}\)

\( =\frac{1}{50}+\frac{1}{50}=\frac{1}{25}\)

f = 25 cm = 0.25 m

Power of lensĀ \( P = \frac{1}{f(in\, meters)}=\frac{1}{0.25}=+4D\)

Answered by Shivani Kumari | 1 year ago

Related Questions

A doctor has prescribed a corrective lens of power +1.5 D. Find the focal length of the lens. Is the prescribed lens diverging or converging?

Class 10 Science Light Reflection and Refraction View Answer

An object of size 7.0 cm is placed at 27 cm in front of a concave mirror of focal length 18 cm. At what distance from the mirror should a screen be placed so that a sharply focused image can be obtained? Find the size and the nature of the image.

Class 10 Science Light Reflection and Refraction View Answer

An object 5 cm is placed at a distance of 20 cm in front of a convex mirror of radius of curvature 30 cm. Find the position, nature, and size of the image.

Class 10 Science Light Reflection and Refraction View Answer