# CBSE Class 10 Physics Lens Formulae

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## Sample Q&A

- f
- Tell concave lens convex lens sign convention
- An object placed in front of the convex lens at a distance of 25cm on the principal axis. The focal length of lens is 15cm, at what distance the image is formed and writes the nature and size of the image.
- A concave lens has focal length of 20 cm. At what distance from the lens a 5 cm tall object be placed so that it forms an image at 15 cm from the lens ? Also calculate the size of the image formed.
- I don't know how to take focal length, image distance and object distance positive or negative in lenses and mirrors?
- what is magnification producer?
- I WANT TO UNDERSTAND LENS FORMULAE
- The magnification of an image formed by a lens is – 1. If the distance of the image from the optical centre of the lens is 35 cm, where is the object placed ? What is the nature and focal length of the lens ? If the object is displaced 20 cm towards the optical centre of the lens, where would the image be formed and what will be its nature ? Draw a ray diagram to justify your answer.
- Answet
- A convex lens has focal length of 30 cm. Calculate at what distance should the object be placed from the lens so that it forms an image at 60 cm on the other side of the lens? Also, find the magnification produced by the lens in this case.

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