Advertisements
Advertisements
प्रश्न
An object is kept at a distance of 1m from a lens of power +2D:
- Identify the type of lens.
- Calculate its focal length and distance of the image formed.
Advertisements
उत्तर
- The given lens is convex because convex lenses have a positive power.
- P = `1/"f"`
+2 = `1/"f"`
f = +0.50 m
Its focal length is +0.50 m.
Using the relation = `1/"f"=1/"v"-1/"u"`
`1/"v"=1/"f"+1/"u"`
= `1/0.5+ (-1)/1`
= `(2+(-1))/1`
v = 1 m
APPEARS IN
संबंधित प्रश्न
A convex lens forms a real and inverted image of a needle at a distance of 50 cm from it. Where is the needle placed in front of the convex lens if the image is equal to the size of the object? Also, find the power of the lens.
The lens mentioned in 6(b) above is of focal length 25cm. Calculate the power of the lens.
Kavita from 10th is using spectacles. The power of the lenses in her spectacles is –2.5 dioptre. Answer the following questions:
1) Which lenses are used in her spectacles?
2) State the defect of vision Kavita is suffering from.
3) Find the focal length of the lenses used in her spectacles
Which one of the following materials cannot be used to make a lens?
Which has more power : a thick convex lens or a thin convex lens, made of the same glass? Give reason for your choice.
The optician's prescription for a spectacle lens is marked +0.5 D. What is the:
(a) nature of spectacle lens?
(b) focal length of spectacle lens?
State the condition for the following a ray passes undeviated through the lens .
Mohan obtained a sharp inverted image of a distant tree on the screen placed behind the lens. He then moved the screen and tried to look through the lens in the direction of the object. He would see:
(1) a blurred image on the wall of the laboratory.
(2) an erect image of the tree on the lens.
(3) no image as the screen has been removed
(4) an inverted image of the tree at the focus of the lens.
A double convex lens has two surfaces of equal radii R and refractive index \[m = 1 \cdot 5\]
