Advertisements
Advertisements
प्रश्न
The focal length of a double convex lens is equal to the radius of curvature of either surface. What is the refractive index of its material?
Advertisements
उत्तर
`1/"f" = ("n"-1) (1/"r"_1 + 1/"r"_2)`
`1/"f" = ("n"-1) (1/"f" + 1/"f")`
`("n"-1) = 1/2`
∴ n = 1.5
APPEARS IN
संबंधित प्रश्न
Find the power of a concave lens of focal length 2m.
Which has more power : a thick convex lens or a thin convex lens, made of the same glass? Give reason for your choice.
Fill in the following blank with suitable words :
The reciprocal of the focal length in metres gives you the _________ of the lens, which is measured in ___________.
The power of a combination of two lenses X and Y is 5 D. If the focal length of lens X be 15 cm :
(a) calculate the focal length of lens Y.
(b) state the nature of lens Y.
State the condition for the following a ray passes undeviated through the lens .
A double convex lens has two surfaces of equal radii R and refractive index \[m = 1 \cdot 5\]
The power of a lens is +2.0 D. Find its focal length and state the kind of lens.
The power of the magnifying glass depends on the distance of the magnifying glass from object.
Match the following:
| Column - I | Column - II | ||
| 1 | Retina | a | Path way of light |
| 2 | Pupil | b | Far point comes closer |
| 3 | Ciliary muscles | c | near point moves away |
| 4 | Myopia | d | Screen of the eye |
| 5 | Hypermetropia | e | Power of accommodation |
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.
