Two conductors having same width and length, thickness d₁ and d₂ thermal conductivity K₁ and K₂ are placed one above the another. Find the equivalent thermal conductivity.

• $\frac{\left({\mathrm{d}}_1+ {\mathrm{d}}_2\right) \left({\mathrm{K}}_1 {\mathrm{d}}_2 + {\mathrm{K}}_2 {\mathrm{d}}_1\right)}{2 \left({\mathrm{K}}_1 + {\mathrm{K}}_2\right)}$

• $\frac{\left({\mathrm{d}}_1 - {\mathrm{d}}_2\right) \left({\mathrm{K}}_1 {\mathrm{d}}_2 + {\mathrm{K}}_2 {\mathrm{d}}_1\right)}{2 \left({\mathrm{K}}_1 + {\mathrm{K}}_2\right)}$

• $\frac{{\mathrm{K}}_1 {\mathrm{d}}_1 + {\mathrm{K}}_2 {\mathrm{d}}_2}{{\mathrm{d}}_1 + {\mathrm{d}}_2}$

• $\frac{{\mathrm{K}}_1 + {\mathrm{K}}_2}{{\mathrm{d}}_{1_{ }}+ {\mathrm{d}}_2}$

Degree of freedom for polyatomic gas

• ≥ 4

• ≥5

• ≥6

• ≥7

A particle moving about its equilibrium position with equation y = -ax - bt. interpret the condition

• It will always perform SHM

• It can never perform the SHM

• It can perform SHM only when t ≥ $\frac{\mathrm{bx}}{\mathrm{a}}$

• It can perform SHM only when t ≤ $\frac{\mathrm{bx}}{\mathrm{a}}$

Conversion of water to steam is accompanied by which process?

• Adiabatic

• Isothermal

• Isochoric

• Cyclic

An ideal gas is taken through the cycle A → B → C → A, as shown in figure. If the net heat supplied to the gas in the cycle is  5 J  the work done by the gas in the process A → B is

• 2 J

• 3 J

• 4 J

• 5 J

What is the slope for an isothermal process?

• $\frac{\mathrm{P}}{\mathrm{V}}$

• $- \frac{\mathrm{P}}{\mathrm{V}}$

• Zero

• ∞

Assertion:  Maximum air flow due to convection does not occur at the north pole but it occurs at 30°N. 

Reason: There is maximum temperature difference between equator and 30° N.

• If both assertion and reason are true and reason is the correct explanation of assertion.

• If both assertion and reason are true but reason is not the correct explanation of assertion.

• If assertion is true but reason is false.

• If both assertion and reason are false.

Assertion:  Surface energy of an oil drop is same whether placed on glass or water surface. 

Reason:  Surface energy is dependent only on the properties of oil.

• If both assertion and reason are true and reason is the correct explanation of assertion.
  
  

• If both assertion and reason are true but reason is not the correct explanation of assertion.

• If assertion is true but reason is false.

• If both assertion and reason are false.

19.

Assertion: Vibrational energy of diatomic molecule corresponding to each degree of  freedom is  k_B T.

Reason:  For every molecule, vibrational degree of freedom is 2.

• If both assertion and reason are true and reason is the correct explanation of assertion.

• If both assertion and reason are true but reason is not correct explanation of assertion.

• If assertion is true but reason is false.

• If both assertion and reason are false.

Assertion:  Turbulence is always dissipative. 

Reason: High reynold number promotes turbulence.

• If both assertion and reason are true and reason is the correct explanation of assertion

• If both assertion and reason are true but reason is not the correct explanation of assertion.

• If assertion is true but reason is false.

• If both assertion and reason are false.