Advertisements
Advertisements
प्रश्न
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.)
Advertisements
उत्तर
`"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
संबंधित प्रश्न
It is said that the assumptions of kinetic theory are good for gases having low densities. Suppose a container is so evacuated that only one molecule is left in it. Which of the assumptions of kinetic theory will not be valid for such a situation? Can we assign a temperature to this gas?
If the molecules were not allowed to collide among themselves, would you expect more evaporation or less evaporation?
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?
The mean square speed of the molecules of a gas at absolute temperature T is proportional to
Find the number of molecules of an ideal gas in a volume of 1.000 cm3 at STP.
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.
If a = 0.72 and r = 0.24, then the value of tr is ______.
At what temperature will oxygen molecules have same rms speed as helium molecules at S.T.P.? (Molecular masses of oxygen and helium are 32 and 4 respectively).
Find the kinetic energy of 5 litres of a gas at STP, given the standard pressure is 1.013 × 105 N/m2.
Compare the rates of emission of heat by a blackbody maintained at 727°C and at 227°C, if the black bodies are surrounded by an enclosure (black) at 27°C. What would be the ratio of their rates of loss of heat?
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 ______
Why the temperature of all bodies remains constant at room temperature?
The average translational kinetic energy of gas molecules depends on ____________.
Explain in detail the kinetic interpretation of temperature.
The graph of kinetic energy against the frequency v of incident light is as shown in the figure. The slope of the graph and intercept on X-axis respectively are ______.
When photons of energy hv fall on a metal plate of work function 'W0', photoelectrons of maximum kinetic energy 'K' are ejected. If the frequency of the radiation is doubled, the maximum kinetic energy of the ejected photoelectrons will be ______.
An ideal gas in a container of volume 500 cc is at a pressure of 2 × 105 N/m2. The average kinetic energy of each molecule is 6 × 10−21 J. The number of gas molecules in the container is ______.
An insulated container containing monoatomic gas of molar mass m is moving with a velocity vo. If the container is suddenly stopped, find the change in temperature.
The Q-value of a nuclear reaction and kinetic energy of the projectile particle, KP are related as ______.
For a particle moving in vertical circle, the total energy at different positions along the path ______.
Two gases A and B are at absolute temperatures of 360 K and 420 K, respectively. The ratio of the average kinetic energy of the molecules of gas B to that of gas A is ______.
When the temperature of an ideal gas is increased from 27°C to 227°C, its speed is changed from 400 ms-1 to vs, and Then vs is ______.
Assuming the expression for the pressure P exerted by an ideal gas, prove that the kinetic energy per unit volume of the gas is `3/2` P.
Show that the average energy per molecule is directly proportional to the absolute temperature ‘T’ of the gas.
2000 calories of radiant heat is incident on a body. If the body absorbs 550 calories of heat, find the coefficient of emmission of the body.
