MAH-MHT CET (PCM/PCB) entrance exam Question Bank Solutions

The maximum wavelength of radiation emitted by a star is 289.8 nm. Then intensity of radiation for the star is ______. 
(Given: Stefan's constant= 5.67 x 10^-8 Wm^-2 K^-4, Wien's constant, b = 2898 µ mK).

Two spherical blackbodies have radii 'r₁' and 'r₂'. Their surface temperature are 'T₁' and 'T₂'. If they radiate same power, then `"r"_2/"r"_1` is ________.

One blackbody at temperature T is surrounded by another blackbody at temperate T₁ (T₁ < T). At T, the radiation emitted by inner blackbody per unit area per second is proportional to ____________.

A mass of 20 kg is suspended from a rope wound on a wheel of diameter 80 cm. The torque about the axis of rotation is ______.

The SI unit and dimensions of Stefan's constant cr in case of Stefan's law of radiation is ______.

A rod I m long is acted upon by a couple as shown in the figure. The moment of couple is τ Nm. If the force at each end of the rod, then magnitude of each force is ______.
(sin 30° = cos 60° = 0.5)

If temperature of black body increases from  17°C to 307°C, then the rate of radiation increases by ______.

An ideal gas occupies a volume 'V' at a pressure 'P' and absolute temperature T. The mass of each molecule is 'm'. If 'Ks' is the Boltzmann's constant, then the density of gas is given by expression ______.

A black rectangular surface of area A emits energy E per second at 27°C. If length and breadth is reduced to `(1/3)^("rd")` of initial value and temperature is raised to 327°C then energy emitted per second becomes ______.

Let '`sigma`' and 'b' be Stefan's cosntant and Wien's constant respectively, then dimensions of '`sigmab`' are ______.

For a heat engine operating between temperatures t₁ °C and t₂ °C, its efficiency will be ______.

Let η₁ is the efficiency of an engine at T₁ = 447°C and T₂ = 147°C while η₂, is the efficiency at T₁ = 947°C and T₂ = 47°C. The ratio `eta_1/eta_2` will be ______.

An ideal gas has pressure 'p' volume 'V' and absolute temperature 'T'. If 'm' is the mass of each molecules and 'K' is the Boltzmann constant, then density of the gas is ______.

At 273°C, the emissive power of a perfectly black body is R. What is its value at 0°C?

A rain drop of radius 0.4 mm has a terminal velocity in air 4 m/s. If the coefficient of viscosity of air is 1.8 x 10^-4 poise, the viscous drag on the rain drop will be ____________.

When a solid ball of volume V is released in a viscous liquid it experiences a viscous force F. If the solid ball of the same material of volume V/2 is released in the liquid then the viscous force will be (where `eta` = coefficient of viscosity) ____________.

The viscous force acting on a small spherical rain drop falling through stormy air cannot be calculated using Stoke's law because ____________.

What will be the approximate terminal velocity of a rain drop of diameter 1.2 x l0^-3 m, when density of rainwater ≈ l0³ kgm^-3 and the co-efficient of viscosity of air ≈ 1.8 x l 0^-5 Nsm^-2? 

A metal sphere of radius 'R' and density 'ρ₁' is dropped in a liquid of density 'σ' moves with terminal velocity 'v'. Another metal sphere of same radius and density 'ρ₂' is dropped in the same liquid, its terminal velocity will be ______.

If α is the coefficient of performance of a refrigerator and 'Q₁' is heat released to the hot reservoir, then the heat extracted from the cold reservoir 'Q₂' is ______.