Q15 of 29 Page 109

Take a thin thermal sheet. Cut it in circular discs of different radii like 2cm, 3cm, 4cm, 4.5cm. 5cm etc ad mark centers with sketch pen. Now take needles of length nearly firm. Pin a needle to each disc at its centre vertically. Take water in a large opaque tray and place the disc with 2cm radius in such a way that the raw& is inside the water ac shown in fig Q15. Now try to view the free end (head) of the needle from surface of the water.


• Does this activity help you to limit he ethical age of the medium (water)?

Yes, we can find the critical angle of the water by applying the Snell’s law at the water and air interface.


Refractive index of water =


⇒


⇒


⇒ c =


⇒ c = 49o.


Hence critical angle of the water is 49o.


More from this chapter

All 29 →
15

Take a thin thermal sheet. Cut it in circular discs of different radii like 2cm, 3cm, 4cm, 4.5cm. 5cm etc ad mark centers with sketch pen. Now take needles of length nearly firm. Pin a needle to each disc at its centre vertically. Take water in a large opaque tray and place the disc with 2cm radius in such a way that the raw& is inside the water ac shown in fig Q15. Now try to view the free end (head) of the needle from surface of the water.


• At what maximum radius of disc, were you not able to see the free end of the needle?

 15

Take a thin thermal sheet. Cut it in circular discs of different radii like 2cm, 3cm, 4cm, 4.5cm. 5cm etc ad mark centers with sketch pen. Now take needles of length nearly firm. Pin a needle to each disc at its centre vertically. Take water in a large opaque tray and place the disc with 2cm radius in such a way that the raw& is inside the water ac shown in fig Q15. Now try to view the free end (head) of the needle from surface of the water.


• Why were you not able to view the head of the nail fix certain radii of the discs?

 15

Take a thin thermal sheet. Cut it in circular discs of different radii like 2cm, 3cm, 4cm, 4.5cm. 5cm etc ad mark centers with sketch pen. Now take needles of length nearly firm. Pin a needle to each disc at its centre vertically. Take water in a large opaque tray and place the disc with 2cm radius in such a way that the raw& is inside the water ac shown in fig Q15. Now try to view the free end (head) of the needle from surface of the water.


• Draw a diagram to show the passage of light ray from the head of the nail in different situations. (AS4)

 16

Explain the refraction of light through a glass slab with a neat ray diagram. (AS5)