WC7_ 24 April

Maxwell-Boltzmann statistics cannot be applied to _____________

• Atoms

• Molecules

• Photons

• Lattice

Answer explanation

Maxwell-Boltzmann can only be applied to particles which are distinguishable. Photons are indistinguishable from one other.

Choose correct formula for <E>

( β = 1/Kb * T ; z : partition function)

• <E>= 1/z dz/dβ

• <E>= -1/z dβ/dz

• <E>= -1/β dz/dβ

• <E>= -1/z dz/dβ

From the figure, what is the highest temperature?

• T1

• T2

• T3

• Not sufficient information

Answer explanation

As we know, as the temperature increases, the maximum velocity of the particle decreases and the density of the particles moving with higher speed increases. Thus, the correct option is T3.

Mass of A is 4 times that of B. What is the ratio of their root mean square velocities?

• 1 : 4

• 4 : 1

• 1 : 2

• 2 : 1

Answer explanation

As we know, mean velocity = √(3kT/M)
Now, M_a = 4M_b
Dividing we get: V_a : V_b = 1:√4
= 1 : 2.

For a given plot what does the area under curve represent according to Maxwell- Boltzmann distribution?

• Total number of molecules per unit acceleration

• Total number of molecule

• Rate of acceleration of particles

• None of the above

Answer explanation

-> From the given plot of Maxwell-Boltzmann distribution we can see that fraction of a number of particles very close to speed v ie (dN/dv) is plotted along the Y-axis and the speed is along X-axis.

-> Thus area under the curve will be given as the total number of molecule

-> Hence area under the curve represents the total number of molecules.

Therefore option 2 is correct.