Questions 51–60 of 60. Imported answers require independent review unless marked reviewed.

Topic practice 60 questionsPage 6 of 6

Question 52

Open question
PHNAT2 marksNeeds review
Two solid spheres A and B have same emissivity. The radius of A is four times the radius of B, and temperature of A is twice the temperature of B. The ratio of the rate of heat radiated from A to that from B is ______.

Log in to check the answer

You can attempt this question now. Sign in to view the answer key, explanations and discussion.Log in to check answer

Question 53

Open question
PHNAT2 marksNeeds review
The partition function of an ensemble at a temperature

is

where

is the Boltzmann constant. The heat capacity of this ensemble at

is

, where the value of X is ______ (up to one decimal place).

Log in to check the answer

You can attempt this question now. Sign in to view the answer key, explanations and discussion.Log in to check answer

Question 55

Open question
PHNAT2 marksNeeds review
The quantum effects in an ideal gas become important below a certain temperature

when de Broglie wavelength corresponding to the root mean square thermal speed becomes equal to the inter-atomic separation. For such a gas of atoms of mass

kg and number density

,

(up to one decimal place).\n\n(

)

Log in to check the answer

You can attempt this question now. Sign in to view the answer key, explanations and discussion.Log in to check answer

Question 9

Open question
PHMCQ1 markNeeds review
Consider a triatomic molecule of the shape shown in the figure below in three dimensions. The heat capacity of the molecule at high temperature (temperature much higher than the vibrational and rotational energy scales of the molecule but lower than its bond dissociation energies) is:
Diagram for Physics question 9

Your answerChoose one option.

Log in to check the answer

You can attempt this question now. Sign in to view the answer key, explanations and discussion.Log in to check answer

Question 24

Open question
PHMCQ1 markNeeds review
A reversible Carnot engine is operated between temperatures

and

(

) with a photon gas as the working substance. The efficiency of the engine is
Your answerChoose one option.

Log in to check the answer

You can attempt this question now. Sign in to view the answer key, explanations and discussion.Log in to check answer

Question 29

Open question
PHNAT2 marksNeeds review
Water freezes at

at atmospheric pressure (

). The densities of water and ice at this temperature and pressure are 1000 kg/m

and 934 kg/m

respectively. The latent heat of fusion is

, the pressure required for depressing the melting temperature of ice by

is ______ GPa. (up to two decimal places)

Log in to check the answer

You can attempt this question now. Sign in to view the answer key, explanations and discussion.Log in to check answer

Question 33

Open question
PHMCQ2 marksNeeds review
Consider

non-interacting, distinguishable particles in a two-level system at temperature

. The energies of the levels are 0 and

, where

. In the high temperature limit (

), what is the population of particles in the level with energy

?
Your answerChoose one option.

Log in to check the answer

You can attempt this question now. Sign in to view the answer key, explanations and discussion.Log in to check answer

Question 38

Open question
PHNAT2 marksNeeds review
The integral

is equal to ________. (up to two decimal places).

Log in to check the answer

You can attempt this question now. Sign in to view the answer key, explanations and discussion.Log in to check answer

Question 43

Open question
PHNAT2 marksNeeds review
The energy density and pressure of a photon gas are given by

and

, where

is the temperature and

is the radiation constant. The entropy per unit volume is given by

. The value of

is ________. (up to two decimal places).

Log in to check the answer

You can attempt this question now. Sign in to view the answer key, explanations and discussion.Log in to check answer

Question 49

Open question
PHMCQ2 marksNeeds review
Consider two particles and two non-degenerate quantum levels 1 and 2. Level 1 always contains a particle. Hence, what is the probability that level 2 also contains a particle for each of the two cases: (i) when the two particles are distinguishable and (ii) when the two particles are bosons?
Your answerChoose one option.

Log in to check the answer

You can attempt this question now. Sign in to view the answer key, explanations and discussion.Log in to check answer