PHYSICS ASSIGNMENT -2
LATENT HEAT AND REFRACTION OF LIGHT
A
1. A slab of ice at -500C is constantly heated till the water attains a temperature of 900C. Draw a
graph showing the change in temperature with time. Label the various parts of the graph
properly.
2. What will be the result of mixing 400g of copper chips at 5000C with 200g of crushed ice at 00C?
specific heat capacity of copper = 0.42 Jg-1K-1,specific latent heat of fusion of ice = 340 Jg-1.
3. It is generally cold after a hail storm than during or before a hail storm. Give reason.
4. Ice cream appears colder to the mouth than water at 00C. Give reason.
5. The figure shows a glass prism placed in minimum deviation position. A ray of light is incident on
face AB.
A
B
(a)
(b)
(c)
6.
7.
C
Copy the diagram and show the refracted ray and the emergent ray
Mark the angle of deviation
State two factor on which the angle of deviation depends
The refractive index of diamond is 2.42. what is meant by this statement?
A ray of monochromatic light is incident from air on a glass slab:
a) Draw a labeled ray diagram showing the change in the path of the ray till it emerges from
the glass slab.
b) Name the two rays that are parallel to each other.
c) Mark the lateral displacement in your diagram.
d) A ray of light from air suffers partial reflection and refraction at the boundary of water. In
the figure given below, which of the ray A,B,C,D and E is the correct
(i) Refracted ray
(ii) partially reflected ray
E
AIR
WATER
D
A
B
C
8. Copy and complete the paths of the rays A, B, C and D in the given diagram, after they reach the
water the water surface and come out in air. Given the critical angle for water = 480
9. If 63 kcal of heat is needed to melt 10kg of lead at its melting point, what is the latent heat of
fusion of lead?
10. A ray of light strikes the surface of a rectangular glass block such that the angle of incidence is (i)
00 and (ii) 420. Sketch a diagram to show the approximate path taken by the ray in each case as
it passes through the glass block and emerges from it.
11. The lateral displacement produced by a parallel faced slab ________________ with an increase
in the angle of incidence and the ____________ of the slab.
12. Draw a neat scale diagram to find the position and nature of the image of an object 3 cm high
and placed 20 cm in front of a convex lens of focal length 12 cm.
LATENT HEAT AND REFRACTION OF LIGHT
B
1. Which requires more heat: 1g ice at 00C or 1g of water at 00C to raise its temperature to 100C?
2. The specific latent heat of fusion of ice is 336Jg-1. Explain the meaning of the statement.
3. The amount of heat energy required to convert 1kg of ice at -100C to water at 1000C is 7,77,000J.
Calculate the specific latent heat of ice. Specific heat capacity of ice = 2100Jkg-1K-1. Specific heat
capacity of water is 4200 Jkg-1K-1.
4. A small electric lamp is moved up and down above the surface of a small pond. When it is 25 cm
above the surface, its image by reflection appears to coincide with the bottom of the pond. If
the refractive index of water is 4/3, calculate the apparent depth of the pond.
5. Express the refractive index µ of a medium:
i)
In terms of velocity of light
ii)
In terms of angle of incidence i in air and the angle of refraction r in a denser medium
iii)
If any light passes from medium I to medium II without any change in direction, what ca
be said about the refractive indices of these media? (angle I is not zero)
6. The refractive index of diamond is 2.42. What is meant by this statement?
7. What is a total reflecting prism? Where is the prism used?
8. A ray of light is entering from medium 1 to medium 2. It is observed that the refractive index of
medium 2 with respect to 1, is 1μ2 < 1, based on the given information identify the rarer medium
and denser medium.
9.
10.
11.
12.
(ii) Based on the principle of reversibility of light explain what will be the value of refractive
index of medium 1, with respect to medium 2.
How much heat is needed to convert 7g of ice at 00C into water at the same temperature?
A block of ice often appears to be surrounded by a “cloud”. Reason it.
A ray of light strikes the surface of a rectangular glass block such that the angle of incidence is (i)
00 and (ii) 420. Sketch a diagram to show the approximate path taken by the ray in each case as
it passes through the glass block and emerges from it.
An object is placed 4cm away from a convex lens of focal length 12 cm. where is the image
formed and what is its magnification? draw a neat scale diagram to find the position of the
image.
LATENT HEAT AND REFRACTION OF LIGHT
C
1. Define critical angle
2. Copy and complete the path of the ray through the prism in each of the following diagrams.
Each one is a 450 -900 – 450 prism. (ray is travelling normal to the surface)
(i)
(ii)
(iii)
(iv)
3. What device other than plane mirror, can be used to turn a ray of light through 1800? Draw a
diagram in support of your answer. Name an instrument in which the device is used.
4. What is meant by the statement “the critical angle of diamond is 240”? How is the critical
angle of the material is related to its refractive index?
5. Mention two differences between reflection of light from a plane mirror and total internal
reflection of light from a prism.
6. The refractive index of diamond is 2.42. What is meant by this statement?
7. A crack in a window pane appears silvery. Give reason
8. Give two differences between reflection and total internal reflection.
9. How does angle of deviation vary with the angle of incidence?
10. State one advantage of using a total reflecting prism as a reflector in place of a plane mirror.
11. Calculate the total amount of heat energy liberated when 1kg of ice at – 100 C melt to water
at 100 C. [take specific heat of water = 4200 Jkg-1K-1
specific latent heat of ice = 3,36,000 Jkg-1, specific heat capacity of ice = 2100 Jkg-1K-1]
12. Mr. X gets an ice cream and Mr. Y gets a cool drink. Both are at 0 C. Explain who will feel
more colder and why?
13. A ray of light strikes the surface of a rectangular glass block such that the angle of incidence
is (i) 00 and (ii) 420. Sketch a diagram to show the approximate path taken by the ray in each
case as it passes through the glass block and emerges from it.
14. An object is placed 10 cm away from a convex lens of focal length 6cm. draw a neat scale
diagram to find the position of the image.