HC Verma - Concepts of Physics Part 1

Book: HC Verma - Concepts of Physics Part 1

Chapter: 18. Geometrical Optics

Subject: Physics - Class 11th

Q. No. 12 of Objective I

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12

A symmetric double convex lens is cut in two equal parts by a plane perpendicular to the principal axis. If the power of the original lens was 4 D, the power of a divided lens will be

Leaving ahead all mathematical formulations, we can answer this by simple intuition. Even after cutting the lens, if we place them together and provide rays of light, commonly we know, it will generate the same image point. So, still, the combined power is 4D. But, after cutting the they became regular and exactly equal halves. And also Power is a scalar property, hence power of each lens, must be 2D.

Chapter Exercises

Short Answer
Objective I
Objective II
Exercises

More Exercise Questions

1

A point source of light is placed in front of a plane mirror.
2

Total internal reflection can take place only if
3

In image formation from spherical mirrors, only paraxial rays are considered because they
4

A point object is placed at a distance of 30 cm from a convex mirror of focal length 30 cm. The image will form at
5

Figure (18-Q2) shows two rays A and B being reflected by a mirror and going as A’ and B’. The mirror
6

The image formed by a concave mirror
7

Figure (18-Q3) shows three transparent media of refractive indices μ1, μ2 and μ3. A point object O is placed in the medium μ2. If the entire medium on the right of the spherical surface has refractive index μ1, the image forms at O’. If this entire medium has refractive index μ3, the image forms at O’’. In the situation shown,
8

Four modifications are suggested in the lens formula to include the effect of the thickness t of the lens. Which one is likely to be correct?
9

A double convex lens has two surfaces of equal radii R and refractive index m=1.5. We have,
10

A point source of light is placed at a distance of 2f from a converging lens of focal length f. The intensity on the other side of the lens is maximum at a distance
11

A parallel beam of light is incident on a converging lens parallel to its principal axis. As one moves away from the lens on the other side on its principal axis, the intensity of light
12

A symmetric double convex lens is cut in two equal parts by a plane perpendicular to the principal axis. If the power of the original lens was 4 D, the power of a divided lens will be
13

A symmetric double convex lens is cut in two equal parts by a plane containing the principal axis. If the power of the original lens was 4 D, the power of a divided lens will be
14

Two concave lenses L1 and L2 are kept in contact with each other. If the space between the two lenses is filled with a material of smaller refractive index, the magnitude of the focal length of the combination
15

A thin lens is made with a material having refractive index μ = 1.5. Both the surfaces of the lens are convex. It is dipped in water (μ = 1.33). It will behave like
16

A convex lens is made of a material having refractive index 1.2. Both the surfaces of the lens are convex. If it is dipped into water (μ = 1.33), it will behave like
17

A point object O is placed on the principal axis of a convex lens of focal length f= 20 cm at a distance of 40 cm to the left of it. The diameter of the lens is 10 cm. An eye is placed 60 cm to right of the lens and a distance h below the principal axis. The maximum value of h to see the image is
18

The rays of different colours fail to converge at a point after going through a converging lens. This defect is called

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