Advertisements
Advertisements
Question
Energy is emitted from a hole in an electric furnace at the rate of 20 W when the temperature of the furnace is 727°C. What is the area of the hole? (Take Stefan’s constant σ to be 5.7 × 10-8 Js-1 m-2K-4.)
Solution
`"Q"/"t" = 20`W, T = 273 + 727 = 1000 K
σ = 5.7 × 10-8 Js-1 m-2K-4.
`"Q"/"t" = sigma"AT"^4`
∴ The area of the hole,
A = `("Q"//"t")/(sigma"T"^4) = 20/((5.7 xx 10^-8)(10^3)^4)` m2
`= (20xx10^-4)/5.7 = 3.509 xx 10^-4` m2
APPEARS IN
RELATED QUESTIONS
Consider a gas of neutrons. Do you expect it to behave much better as an ideal gas as compared to hydrogen gas at the same pressure and temperature?
A gas is kept in an enclosure. The pressure of the gas is reduced by pumping out some gas. Will the temperature of the gas decrease by Charles's low?
Is it possible to boil water at room temperature, say 30°C? If we touch a flask containing water boiling at this temperature, will it be hot?
When you come out of a river after a dip, you feel cold. Explain.
The pressure of an ideal gas is written as \[P = \frac{2E}{3V}\] . Here E refers to
The process on an ideal gas, shown in figure, is
Which of the following quantities is the same for all ideal gases at the same temperature?
(a) The kinetic energy of 1 mole
(b) The kinetic energy of 1 g
(c) The number of molecules in 1 mole
(d) The number of molecules in 1 g
The average translational kinetic energy of air molecules is 0.040 eV (1 eV = 1.6 × 10−19J). Calculate the temperature of the air. Boltzmann constant k = 1.38 × 10−23 J K−1.
The mean speed of the molecules of a hydrogen sample equals the mean speed of the molecules of a helium sample. Calculate the ratio of the temperature of the hydrogen sample to the temperature of the helium sample.
Use R = 8.314 JK-1 mol-1
Air is pumped into the tubes of a cycle rickshaw at a pressure of 2 atm. The volume of each tube at this pressure is 0.002 m3. One of the tubes gets punctured and the volume of the tube reduces to 0.0005 m3. How many moles of air have leaked out? Assume that the temperature remains constant at 300 K and that the air behaves as an ideal gas.
Use R = 8.3 J K-1 mol-1
The weather report reads, "Temperature 20°C : Relative humidity 100%". What is the dew point?
The temperature and the dew point in an open room are 20°C and 10°C. If the room temperature drops to 15°C, what will be the new dew point?
A glass contains some water at room temperature 20°C. Refrigerated water is added to it slowly. when the temperature of the glass reaches 10°C, small droplets condense on the outer surface. Calculate the relative humidity in the room. The boiling point of water at a pressure of 17.5 mm of mercury is 20°C and at 8.9 mm of mercury it is 10°C.
If a = 0.72 and r = 0.24, then the value of tr is ______.
Answer in brief:
A gas in a cylinder is at pressure P. If the masses of all the molecules are made one-third of their original value and their speeds are doubled, then find the resultant pressure.
Explain, on the basis of the kinetic theory of gases, how the pressure of a gas changes if its volume is reduced at a constant temperature.
The number of degrees of freedom, for the vibrational motion of a polyatomic molecule, depends on the ______
The power radiated by a perfect blackbody depends only on its ______
What is the microscopic origin of temperature?
Explain in detail the kinetic interpretation of temperature.
Average kinetic energy of H2 molecule at 300K is 'E'. At the same temperature, average kinetic energy of O2 molecule will be ______.
Consider a rectangular block of wood moving with a velocity v0 in a gas at temperature T and mass density ρ. Assume the velocity is along x-axis and the area of cross-section of the block perpendicular to v0 is A. Show that the drag force on the block is `4ρAv_0 sqrt((KT)/m)`, where m is the mass of the gas molecule.
The Q-value of a nuclear reaction and kinetic energy of the projectile particle, KP are related as ______.
Which of the following materials is diathermanous?
