Advertisements
Advertisements
Question
If a = 0.72 and r = 0.24, then the value of tr is ______.
Options
0.02
0.04
0.4
0.2
Advertisements
Solution
If a = 0.72 and r = 0.24, then the value of tr is 0.04.
Explanation:
Express the relation of absorptivity. The fraction of light/ray/radiation absorbed by a surface is called absorptivity.
`a = (G_(abs))/G`
`G_(abs) =Ga`
Here, `G_(abs)` is absorbed radiation and G is incident radiation.
Express the relation of reflectivity.
The fraction of light reflected by a surface is known as reflectivity.
`r = (G_(ref))/G`
`G_(ref) = Gr`
Here, `G_(ref)` is reflected radiation.
Express the relation of transmissivity. The fraction of light/ray/radiation transmitted by a surface is known as transmissivity.
`t_r = G_t/G`
`G_t = Gt_r`
Here, `G_t` is transmitted radiation.
Express the relation of 1st law of thermodynamics. Sum of all radiation (absorbed, reflected and transmitted) should be equals to the total radiation.
`G_(abs) + G_(ref) + G_t = G` ......(i)
Substitute `Ga` for `G_(abs), G_r` for `G_(mf)` and Gt for Gt in equation (i).
`(Ga)/G + (Gr)/G + (Gt_r)/G` = 1
`a + r + t_r` = 1
Substitute 0.72 for a and 0.24 for r to find transmitted radiation.
0.72 + 0.24 + tr = 1
tr = 1 – 0.96
tr = 0.04
APPEARS IN
RELATED QUESTIONS
Do you expect the gas in a cooking gas cylinder to obey the ideal gas equation?
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?
When you come out of a river after a dip, you feel cold. Explain.
The mean square speed of the molecules of a gas at absolute temperature T is proportional to
During an experiment, an ideal gas is found to obey an additional law pV2 = constant. The gas is initially at a temperature T and volume V. Find the temperature when it expands to a volume 2V.
Use R = 8.3 J K-1 mol-1
Figure shows two vessels A and B with rigid walls containing ideal gases. The pressure, temperature and the volume are pA, TA, V in the vessel A and pB, TB, V in the vessel B. The vessels are now connected through a small tube. Show that the pressure p and the temperature T satisfy `Ρ/T = 1/2 ({P_A}/{T_A}+{P_B}/{T_B))` when equilibrium is achieved.
An adiabatic cylindrical tube of cross-sectional area 1 cm2 is closed at one end and fitted with a piston at the other end. The tube contains 0.03 g of an ideal gas. At 1 atm pressure and at the temperature of the surrounding, the length of the gas column is 40 cm. The piston is suddenly pulled out to double the length of the column. The pressure of the gas falls to 0.355 atm. Find the speed of sound in the gas at atmospheric temperature.
Answer in brief:
What will happen to the mean square speed of the molecules of a gas if the temperature of the gas increases?
Answer in brief:
Show that rms velocity of an oxygen molecule is `sqrt2` times that of a sulfur dioxide molecule at S.T.P.
Compare the rms speed of hydrogen molecules at 127°C with rms speed of oxygen molecules at 27ºC given that molecular masses of hydrogen and oxygen are 2 and 32 respectively.
When a gas is heated, its temperature increases. Explain this phenomenon on the basis of the kinetic theory of gases.
The emissive power of a sphere of area 0.02 m2 is 0.5 kcal s-1m-2. What is the amount of heat radiated by the spherical surface in 20 seconds?
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?
Compare the rate of radiation of metal bodies at 727 °C and 227 °C.
A metal cube of length 4 cm radiates heat at the rate of 10 J/s. Find its emissive power at a given temperature.
The average translational kinetic energy of a molecule in a gas becomes equal to 0.49 eV at a temperature about (Boltzmann constant = 1.38 x 10-23 JK-1) ____________.
Assuming the expression for the pressure exerted by the gas on the wall of the container, it can be shown that pressure is ______.
A molecule consists of two atoms each of mass 'm' and separated by a distance 'd'. At room temperature the average rotational kinetic energy is 'E', then its angular frequency is ______.
A cylinder containing an ideal gas is in vertical position and has a piston of mass M that is able to move up or down without friction (Figure). If the temperature is increased ______.
Volume versus temperature graphs for a given mass of an ideal gas are shown in figure at two different values of constant pressure. What can be inferred about relation between P1 and P2?
Two molecules of a gas have speeds of 9 × 10 6 ms−1 and 1 × 106 ms−1, respectively. What is the root mean square speed of these molecules?
The Q-value of a nuclear reaction and kinetic energy of the projectile particle, KP are related as ______.
A proton, a deuteron and an α-particle with same kinetic energy enter into a uniform magnetic field at right angle to magnetic field. The ratio of the radii of their respective circular paths is ______.
When a particle oscillates simple harmonically, its kinetic energy varies periodically. If frequency of the particle is n, then the frequency of the kinetic energy is ______.
If a = 0. 72 and t = 0.04, then the value of r is ______.
At what temperature will therms velocity of a gas be four times its value at STP?
If a = 0. 72 and r = 0.24, then the value of t is ______.
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.
