Copy the diagram given below and complete the path of the light ray till it emerges out of the prism. The critical angle of glass is 42o. In your diagram mark the angles wherever necessary.
The traversal of ray is as shown below:
What do you understand by the following statements:
i) The heat capacity of the body is 60 JK-1
ii) The specific heat capacity of lead is 130 Jkg-1 K-1
i) Heat capacity is the amount of heat required to raise the temperature of a body by 1o C or 1 K.
Thus, by this statement, we mean that the amount of heat that is required to raise the temperature of a body by 1 K is 60 JK-1.
ii) Specific heat capacity is the amount of heat energy required to raise the temperature of a unit mass of a substance through 1o C or 1 K. Thus, 130 J kg-1 K-1 is the amount of heat energy required to raise the temperature of unit mass of lead through 1 K.
With reference to the terms Mechanical Advantage, Velocity Ratio and efficiency of a machine, name and define the term that will not change for machine of a given design.
Velocity ratio will not change for the machine of a given design.
It is defined as the ratio of the velocity of effort to the velocity of the load.
A boy uses blue colour of light to find the refractive index o fglass. He then repeats the experiment using red colour of light. Will the refractive index be the same or different in the two cases? Give a reason to support your answer.
The refractive index will be different in both cases.
Refractive index of glass is different for different colours. The speed of blue light is less than the speed of red light. So, the wavelength of blue light is less than that of red light. Thus, the red light would deviate less than blue light because of difference in wavelength.
Calculate the mass of ice required to lower the temperature of 300 g of water from 40o C to water at 0o C.
[Specific latent heat of ice = 336 J/g, specific heat capacity of water = 4.2 J/go C]
Let m be the mass of the ice that has to be added.
Heat energy required to melt to lower the temperature = mL = m x 336
Heat energy imparted by the water in fall of its temperature from 40o C to 0o C
= mass of water x specific heat capacity x fall in temperature
= 300 x 4.2 x 40o
If there is no loss of heat,
The ratio of amplitude of two waves is 3:4. What is the ratio of their:
(i) loudness? (ii) Frequencies?
a1 and a2 be the amplitudes
I1 and I2 be the intensities of the two waves.
ii) Frequency is the number of waves formed per second. It only depends on time period. Thus, the ratio of their frequencies is 1:1.
A boy weighing 40 kgf climbs up a stair of 30 steps each 20 cm high in 4 minutes and a girl weighing 30 kgf does the same in 3 minutes.
(i) The work done by them.
(ii) The power developed by them
Weight of the boy = force of gravity of the boy = 40 kgf
Time taken by the boy,tb = 4minutes = 4 x 60 s = 240 s
Weight of the girl= Force of gravity of the girl, Fg = 30 kgf
Time taken by the girl, tg = 3 minutes = 3 x 60 s = 180 s
Distance covered by both in 30 steps is,
D = 30 x 20 = 600 cm
While climbing upstairs, both have to do work against the force of gravity.
i) Work done by the boy in climbing the stairs is,
Wb = F x D = 40 kgf x 600 cm
i.e., Wb = 24000 J
Work done by the girl in climbing the stairs is:
Wg = F x D = 30 kgf x 600 cm
Wg = 18000 J
ii) Power developed =
Power developed =
Power developed =
Therefore, the power developed by them is 1:1
State the dependence of angle of deviation:
(i) On the refractive index of the material of the prism.
(ii) On the wavelength of light
(i) For a given angle of incidence, the prism with higher refractive index produces a greater deviation than the prism which has a lower refractive index. Thus, the angle of deviation increases with an increase in the refractive index of the medium.
(ii) The angle of deviation decreases with an increase in the wavelength of light. Thus, a prism deviates violet light the most and red light the least.
State two factors upon which the heat absorbed by a body depends:
Heat absorbed by a body depends on the mass of the body and the specific heat capacity of the body.