Advertisements
Advertisements
Question
Two bodies A and B having equal surface areas are maintained at temperature 10°C and 20°C. The thermal radiation emitted in a given time by A and B are in the ratio
Options
1 : 1.15
1 : 2
1 : 4
1 : 16
Advertisements
Solution
1 : 1.15
From Stefan-Boltzmann law, energy of the thermal radiation emitted per unit time by a blackbody of surface area A is given by `u = σAT^4 `
Here, `σ` is Stefan-Boltzmann constant.
`(uA)/(uB)` = `"T"_"A"^4/(T_B^4)`
`(u_A)/ (u_B) = ( 273 +10 )^4/ (273 + 20 )^4`
`uA/uB = 1/1.15`
APPEARS IN
RELATED QUESTIONS
Explain why the earth without its atmosphere would be inhospitably cold
Two identical metal balls one at T1 = 300 K and the other at T2 = 600 K are kept at a distance of 1 m in a vacuum. Will the temperatures equalise by radiation? Will the rate of heat gained by the colder sphere be proportional to `t_2^4 - t_1^4` as may be expected from the Stefan's law?
Standing in the sun is more pleasant on a cold winter day than standing in shade. Is the temperature of air in the sun considerably higher than that of the air in shade?
Why is a white dress more comfortable than a dark dress in summer?
A solid at temperature T1 is kept in an evacuated chamber at temperature T2 > T1. The rate of increase of temperature of the body is proportional to
A heated body emits radiation which has maximum intensity near the frequency v0. The emissivity of the material is 0.5. If the absolute temperature of the body is doubled.
(a) the maximum intensity of radiation will be near the frequency 2v0
(b) the maximum intensity of radiation will be near the frequency v0/2
(c) the total energy emitted will increase by a factor of 16
(d) the total energy emitted will increase by a factor of 8
Assume that the total surface area of a human body is 1.6 m2 and that it radiates like an ideal radiator. Calculate the amount of energy radiated per second by the body if the body temperature is 37°C. Stefan constant σ is 6.0 × 10−8 W m−2 K−4.
A cylindrical rod of length 50 cm and cross sectional area 1 cm2 is fitted between a large ice chamber at 0°C and an evacuated chamber maintained at 27°C as shown in the figure. Only small portions of the rod are inside the chamber and the rest is thermally insulated from the surrounding. The cross section going into the evacuated chamber is blackened so that it completely absorbs any radiation falling on it. The temperature of the blackened end is 17°C when steady state is reached. Stefan constant σ = 6 × 10−8 W m−2 K−4. Find the thermal conductivity of the material of the rod.
Calculate the amount of heat radiated per second by a body of surface area 12 cm2 kept in thermal equilibrium in a room at temperature 20°C. The emissivity of the surface = 0.80 and σ = 6.0 × 10−8 W m−2 K−4.
Wein's constant is 2892 × 10-6 SI unit and the value of λm for moon is 14.46 micron. The surface temperature of moon is ______.
A student says, "Heat from the Sun reaches Earth because air carries it across space." Which statement best explains why this is incorrect?
Which statement best describes thermal radiation from everyday objects like trees, roads, and buildings at night?
Two identical metal tins with water are kept in sunlight. One is black and the other shiny. Why does water in the black tin become hotter?
Why are cooking utensils like pans made of metal but fitted with plastic or wooden handles?
According to Stefan–Boltzmann Law, if the temperature of a body is doubled (in Kelvin), the heat emitted by it becomes ______.
In the experiment where a test tube of water is heated from the top with ice at the bottom, the ice does not melt. What is the primary reason for this?
Which of the following properties is shared by both thermal radiation and visible light?
