What happens to their focal lengths when they are immersed in a medium of refractive index higher than that of air?

Given that, the refractive index of the material of the lens is greater than that of water. Thus, the focal length is inversely proportional to the refractive index. ∴fw>fa where fw is the focal length of the lens in water and fa is the focal length of the lens in air.

What happens when focal length immersed in water?

What happens to focal length of a convex lens when it is immersed in water ? ∴fw>fa, i.e., focal length of lens will increase.

Does the focal length of lens change when immersed in water?

Yes. Focal length changes when lens is immersed in water.

What happens when focal length of lens increases?

The longer the focal length, the narrower the angle of view and the higher the magnification. The shorter the focal length, the wider the angle of view and the lower the magnification.

What if convex lens is dipped in water?

When a convex lens is dipped in water its focal length changes and relative refractive index changes which makes it less converging.

What happens if lens kept in water?

focal length depends upon refractive index of lens with respect to medium. hence, after immersing of lens in water focal length of lens increases.

What is the distance of far point of a normal eye?

25 cm
For a normal human eye, this distance is 25 cm. Hypermetropia is a condition in which the eye can’t see close objects properly….Thank you.

When a convex lens is kept in water?

Now since the focal length is inversely proportional to the (μ−1), therefore the focal length will increase. Hence the focal length of the lens increases when it is immersed in the water. Hence, Option A is correct. Note: We compare the refraction from one medium to another by their refractive index.

How do you tell if a lens is concave or convex?

Lenses may be divided broadly into two main types: convex and concave. Lenses that are thicker at their centers than at their edges are convex, while those that are thicker around their edges are concave. A light beam passing through a convex lens is focused by the lens on a point on the other side of the lens.

What is the difference between one lens and another that is more powerful than it?

Such a lens is called a converging (or convex) lens for the converging effect it has on light rays. The greater effect a lens has on light rays, the more powerful it is said to be. A powerful converging lens will focus parallel light rays closer to itself and will have a smaller focal length than a weak lens.

Which lens has more power?

Thick convex lens
Thick convex lens has more power because of its shorter focal length.

1. Refraction:

(i) The phenomenon of bending of light entering from one medium to another is called refraction of light.

(ii) When a ray of light travels from a rarer medium to a denser medium, it bends towards the normal.

(iii) When a ray of light travels from a denser medium to a rarer medium, it bends away from the normal.

(iv) There are two laws of refraction.

(a) First Law: The incident ray, the refracted ray and the normal at the point of incidence, all lie on the same plane.

(b) Second Law: The ratio of sine of angle of incidence to the sine of angle of refraction is constant for a given pair of media. This is also called Snell’s law.

2. Refractive Index: 

(i) Refractive index (n) of a medium is the ratio of speed of light in vacuum (c) to the speed of light in the medium (v) and is given by n=cv.

(ii) Refractive index of one medium w.r.t to another medium is given by, n21=Speed of light in medium 1Speed of light in medium 2.

3. Reversibility of light:

When a light ray, after suffering many reflections and refractions, has its final path reversed and travels back along its initial path is called principle of reversibility of light.

4. Lateral displacement: 

The perpendicular distance of separation between the incident ray and the emergent ray is called lateral displacement.

5. The apparent depth: 

The shift by which an object appears to be raised when it is immersed in water is called the apparent depth. Refractive Index=Real depthApparent depth.

6. Advances sunrise and delayed sunset:

Advanced sunrise and delayed sunset, the twinkling of stars and shimmering effect around a campfire are some consequences of refraction. 

7. Prism:

(i) A transparent refracting medium bounded by five plane surfaces inclined at some angles is known as a prism.

(ii) The angle between two refracting surfaces is called angle of prism (A) and the angle between the incident ray and the emergent ray is called the angle of deviation (D).

(iii) The refractive index of the prism, n=sinDmin+A2sinA2

8. Total internal reflection: 

(i) Critical angle for a pair of media is defined as the angle of incidence in denser medium for which the angle of refraction becomes 90°.

(ii) When a ray of light is travelling from a denser medium to rarer medium, is incident at the interface of the two media at an angle greater than the critical angle, the ray is totally reflected back to the denser medium. This phenomenon is called total internal reflection.

What happens to the focal length of a convex lens when it is immersed in water?

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Text Solution

Solution : From lens maker's formula <br> `(1)/(f) = (mu - 1)((1)/(R_1)-(1)/(R_2))` <br> `:. f prop (1)/((mu - 1))` <br> As `.^w mu_g lt .^a mu_g` <br> `:. f_w gt f_a`, i.e., focal length of lens will increase.

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