State and define the S.I. unit of power of a lens.
Download our app for free and get started
Power of lens is the ability of the lens to converge the rays of light falling on it. It can also be defined as $\text{P}=\frac{1}{\text{f}}$ where f is the focal length. Dioptre is the S.I. unit of power of lens. One Dioptre is the power of a lens whose focal length is 1 metre.
Download our appand get started for free
Experience the future of education. Simply download our apps or reach out to us for more information. Let's shape the future of learning together!No signup needed.*
Similar Questions
- 1View SolutionDraw ray diagrams showing the image formation by a concave mirror when an object is placed:
At centre of curvature of the mirror. - 2View SolutionA student focuses the image of a candle flame, placed at about 2 m from a convex lens of focal length 10 cm, on a screen. After that he moves gradually the flame towards the lens and each time focuses its image on the screen.
- In which direction does he move the lens to focus the flame on the screen?
- What happens to the size of the image of the flame formed on the screen?
- What difference is seen in the intensity (brightness) of the image of the flame on the screen?
- What is seen on the screen when the flame is very close (at about 5 cm) to the lens?
- 3View SolutionAn object is placed just outside the principal focus of concave mirror. Draw a ray diagram to show how the image is formed, and describe its size, position and nature.
- 4View SolutionAt what distance from a converging lens of focal length 12cm must an object be placed in order that an image of magnification 1 will be produced?
- 5View SolutionAn object is placed at a distance of 12cm in front of a concave mirror of radius of curvature 30cm. List four characteristics of the image formed by the mirror.
- 6The speed of light in water is $2.25 \times 10^8 m / s$. If the speed of light in vacuum be $3 \times 10^8 m / s$, calculate the refractive index of water.View Solution
- 7View SolutionRefractive indices of four media A, B, C and D are given below:
In which of these four media is the speed of light:MediumRefractive indexABCD1.331.441.521.65- Maximum, and
- Minimum?
- 8View SolutionState one practical application the use of such a lens with the object in position (i) and (ii).
- 9View SolutionA convex lens of power 5D and a concave lens of power 7.5D are placed in contact with each other. What is the:
- Power of this combination of lenses?
- Focal length of this combination of lenses?
- 10View SolutionA 5cm tall object is placed perpendicular to the principal axis of a convex lens of focal length 18cm at a distance of 12cm from it. Use lens formula to determine the position, size and nature to the image formed.