Physics
Complete the path of the rays of light incident on a convex lens of refractive index μ1, when it is kept in medium of different refractive index μ2.
(a) μ1 > μ2
(b) μ1 = μ2
(c) μ1 < μ2
Answer
(a) When the refractive index of the lens is greater than that of the surrounding medium, the convex lens behaves as a converging lens. The incident parallel rays refract towards the principal axis after passing through the lens and meet at a real focus on the other side.
(b) When the refractive index of the lens and the surrounding medium are equal, there is no refraction at all and the lens effectively becomes optically invisible.
The incident rays pass straight through without any deviation and hence no image is formed because the lens has zero optical power.
(c) When the refractive index of the lens is less than that of the surrounding medium, the convex lens behaves like a diverging lens. The incident parallel rays spread out after passing through the lens and appear to diverge from a virtual focus on the same side as the incident rays.
Related Questions
In figure (a) and (b), F1 and F2 are the positions of the two foci of thin lenses. Draw the path taken by the light ray AB after it emerges from each lens.
(a) Figure a
(b) Figure b
In figure (a) and (b), F1 and F2 are the two foci of thin lenses and AB is the incident ray. Complete the diagram to show the path of the ray AB after refraction through each lens.
(a) Figure a
(b) Figure b
Which of the ray diagrams are correct ?
1.
2.
3.
4.
Identify the incorrect statement :
- A real image is formed due to actual intersection of the rays refracted by the lens.
- A virtual image can be obtained on the screen.
- A virtual image is erect with respect to the object.
- A real image is inverted with respect to the object.