Principle of Reversibility of Light

Q.

The refractive index of glass with respect to air is $\frac{3}{2}$. The refractive index of air with respect to glass will be?

Q.

The focal length of a convex lens is $30cm$ and the size of the image is half of the object. The object distance is

1. $90cm$

2. $60cm$

3. $30cm$

4. $40cm$

Q. A convex lens of crown glass (n = 1.525) will behave as a divergent lens if immersed in:

1. water (n = 1.33)
2. in a medium (n = 1.525)
3. carbon disulphide (n = 1.66)
4. it cannot act as a divergent lens

Q. When a ray of light enters a medium of refractive index $\mu$ from air. It is observed that the angle of refraction is half the angle of incidence. The angle of incidence is :

1. $2co{s}^{-1}\left(\frac{\mu }{2}\right)$
2. $co{s}^{-1}\left(\frac{\mu }{2}\right)$
3. $2co{s}^{-1}\left(\mu \right)$
4. $2si{n}^{-1}\left(\frac{\mu }{2}\right)$

Q.

The refractive index of water is 4/3 and that of glass is 3/2. Calculate the refractive index of glass with respect to water.

Q. How does Fermats principle of least time prove that light always retraces its path?

Q.

Fermat’s principle of least time can be used to prove the following statement. Explain how?

Light always retraces its path.

Q.

What will happen to a ray of light if it falls normally on a surface?

Q. Principle of reversibility.

Q. A point source of light is placed at a depth $h=0.5m$ below the surface of a liquid $\left(\mu =\frac{5}{4}\right)$. Then, the fraction of light energy that escape directly from the liquid surface is :-

1. $0.1$
2. $0.2$
3. $0.3$
4. $0.4$

Q. Principle of reversibility can applied to

1. Lens system
2. Mirror system
3. Lens and mirror system
4. None of these

Q. A convex lens made of material of refractive index n 2 is kept in a medium of refractive index n1. A parallel beam of light is incident on the lens. Compare the path of rays of light emerging from the convex lens if (i) n1 < n2 (ii) n1 = n2 (iii) n1 > 1.

Q. If anything, achieves a velocity faster than that of light ...then can it pass through opaque objects? Which light can not do because of its constant speed.

Q.

List four characteristics of the images formed by plane mirrors. [3 Marks ]

Q. A ray of light passes normally through a slab $(\mu =1.5)$ of thickness t . If the speed of the light in vacuum be c , then time taken by the ray to go across the slab will be

Q. _____________ states that when final path of a ray of light after any number of reflections and refractions is reversed, the ray retraces its entire path.

1. Principle of reversibility
2. Law of reflection
3. Law of refraction
4. None of these

Q. Assertion :The principle of reversibility presupposes that the attenuation of a light ray during its passage through an optical medium because of reflection, refraction, and absorption is not affected by a reversal of the direction of the ray. Reason: Principle of reversibility can only be applied to lens system.

1. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
2. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
3. Assertion is correct but Reason is incorrect
4. Both Assertion and Reason are incorrect

Q. Reversibility is a property seen in

1. sound wave
2. light wave
3. both A and B
4. none of A and B

Q. The _____________ states that light will follow exactly the same path if its direction of travel is reversed. Fill the appropriate answer.

1. Newton's law of motion
2. Laws of reflection
3. Laws of refraction
4. Principle of reversibility

Q. At ray of light is incident in medium 1 at an angle of ${37}^o$ and gets refracted in medium 2 at an angle of ${53}^o$. What will be angle of refraction if light is incident in medium 2 at an angle of ${53}^o$.

1. ${45}^o$
2. ${37}^o$
3. ${53}^o$
4. ${36}^o$

Q. A thin convex lens having aperture diameter d forms an image of intensity I. Now the central part of the aperture upto diameter $\frac{d}{2}$ is blocked by an opaque paper. The image intensity will

द्वारक व्यास d वाला एक पतला उत्तल लेन्स I तीव्रता का एक प्रतिबिम्ब निर्मित करता है। अब द्वारक के केन्द्रीय भाग को $\frac{d}{2}$ व्यास तक किसी अपारदर्शी कागज द्वारा ढका जाता है। प्रतिबिम्ब की तीव्रता

1. Decrease
   
   घटेगी
2. Increase
   
   बढ़ेगी
3. Remain same
   
   समान रहेगी
4. May increase or decrease
   
   बढ़ या घट सकती है

Q. If the set up has been immersed in water, what has changed?

1. ${\mu }_1$
2. u
3. R
4. ${\mu }_2$

Q. Principle of reversibility holds true for

1. Reflection
2. Refraction
3. Reflection and Refraction
4. None of these

Q. In its simplest interpretation the principle of reversibility is a corollary of __________ of the refraction of light.

1. Snell's law
2. Law of refraction
3. Law of reflection
4. None of these

Q. A beam of light travelling in air is incident on water . Draw a ray diagram indicating the change in its path in water .

Q.

Question 14
The path of a ray of light coming from air passing through a rectangular glass slab traced by four students are shown as A, B, C and D in figure. Which one of them is correct?



(a) A
(b) B
(c) C
(d) D

Q.

Which of the following ray diagram is correct?

Q. The refractive index of water is $\frac{4}{3}$ and of glass is $\frac{3}{2}$. What will be the refractive index of glass with respect to water?

1. $9.1$
2. $1$
3. $1.125$
4. $2.623$

Q. Which component of the mirror reflects the light?

1. Front side of glass
2. Silver polishing
3. Opaque paint at the back
4. Back side of glass

Q. Assertion :The Helmholtz reciprocity principle describes how a ray of light and its reverse ray encounter matched optical adventures, such as reflections, refractions and absorptions in a passive medium, or at an interface. Reason: Light has dual nature so it follows the law of collision of particles.

1. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
2. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
3. Assertion is correct but Reason is incorrect
4. Both Assertion and Reason are incorrect