1. The speed of light in vacuum is ……….. 2. Power of a lens is the ………. of its focal length. 3. The SI unit of power is ……….. 4. A ………. lens will always give a virtual, erect and diminished image, irrespective of the position of the object. 5. A positive sign in the value of magnification indicates that the image is ………. . 6. Focal length of lens, having power – 5D, will be ___________ 7. Focal length of a convex lens is 2 m. The power of lens wil
Answers
Answer:
1)approximatel
2) power of a lens is defined as the reciprocal of the focal length. Lens power is measured in dioptres (D). Converging (convex ) lenses have positive focal lengths, so they also have positive power values. Diverging (concave ) lenses have negative focal lengths, so they also have negative power values
3)WATT
4)A concave lens will always give a virtual, erect and diminished image, irrespective of the position of the object
5)A positive sign in the value of magnification indicates that the image is virtual. Magnification is the increase in the image size produced by spherical mirrors concave or convex with respect to the object size.
6)The focal length of the lens is 20 cm.
7)The power of the lens is said to be 1 dioptre if the focal length of the lens is 1metre. That means, if the corrective power of the lens is +0.5D, the required lens is a convex lens of focal length +2m. In the same way, a power of -2.0D means a concave lens of focal length -0.5m.
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