Question

Q.1. Define power of a lens.
Q.2. Define the SI unit of power of a lens.
Q.3. Write the lens formula.
Q.4. Where should an object be placed in front of convex lens to get an image of equal size?
Q.5. For what position of the object does a convex lens form a virtual and erect image? ​

Answer 1

Answer:

Here is your some answer

Explanation:

1. Power of lens

P = 1/f

half of focus lenths

2. cm

3. 1/f = 1/v-1/u

Answer 2

Answer

1. If a lens has a shorter focal length it is said to be more powerful. The power of a lens is defined as the reciprocal of the focal length. Converging (convex ) lenses have positive focal lengths, so they also have positive power values.
2. Power of lens is known as the inverse of the focal length of the lens measured in meter(m). S.I unit of power = Dioptre (D) Power of lense = 1/ focal length in meter.
3. Calculating magnification with the help of lens formula:
4. Magnification of a lens is defined as the ratio of the height of an image to the height of an object. It is also given in terms of image distance and object distance. It is equal to the ratio of image distance to that of object distance.
5. At twice the focal length, the image formed by the convex lens is real and of the same size as the object. If the lens has a focal length of 20 cm, the object must be positioned 40 cm in front of the lens, creating an inverted image of the same size as the target, 40 cm behind the lens.
6. When an object is placed between the focus and the optical centre of a convex lens, a virtual and erect image of the object is formed.

Explanation:

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