Advertisements
Advertisements
प्रश्न
What does sign of power (+ve or –ve) indicate?
Advertisements
उत्तर
Positive power (+ve) of a lens indicates converging ability of a lens as in the case of convex lens, and negative power (−ve) of a lens indicates its diverging ability as in the case of concave lens.
APPEARS IN
संबंधित प्रश्न
Find the focal length of a lens of power −2.0 D. What type of lens is this?
Give the usual name for the following:
A point inside a lens through which the light passes undeviated.
How is the power of a lens related to its focal length?
Find the radius of curvature of the convex surface of a plano-convex lens, whose focal length is 0.3 m and the refractive index of the material of the lens is 1.5.
A convex lens produces a double size real image when an object is placed at a distance of 18 cm from it. Where should the object be placed to produce a triple size real image?
Surabhi from std. X uses spectacle. The power of the lenses in her spectacle is 0.5 D.
Answer the following questions from the given information:
- Identify the type of lenses used in her spectacle.
- Identify the defect of vision Surabhi is suffering from.
- Find the focal length of the lenses used in her spectacle.
A lens forms an upright and diminished image of an object, irrespective of its position. What kind of lens is this? Draw an outline ray diagram to show the formation of the image. State the position and one more characteristic of the image.
Increase in the converging power of eye lens cause ‘hypermetropia'
Assertion and reasoning type
- Assertion: Myopia is due to the increase in the converging power of eye lens.
- Reason: Myopia can be corrected with the help of concave lens.
The power of a lens placed in a medium is given by:
