Chapter 22 – Heat Transfer
Three discs A,B and C having radii 2m,4m, and 6m respectively are coated with carbon black on their outer surfaces. The wavelength corresponding to maximum intensity are 300nm,400nm and 500nm respectively. The power radiated by them are QA , QB and QC respectively.
10
Sep
Three discs A,B and C having radii 2m,4m, and 6m respectively are coated with carbon black on their outer surfaces. The wavelength corresponding to maximum intensity are 300nm,400nm and 500nm respectively. The power radiated by them are QA , QB and QC respectively. 400nm and 500nm respectively. The power radiated by them are QA 4m [...]
A heated body emits radiation which has maximum intensity near the frequency vo. The emissivity of the material is 0.5. If the absolute temperature of the body is doubled. Then :
10
Sep
A heated body emits radiation which has maximum intensity near the frequency vo. The emissivity of the material is 0.5. If the absolute temperature of the body is doubled. Then : A heated body emits radiation which has maximum intensity near the frequency vo. The emissivity of the material is 0.5. If the absolute temperature [...]
The power radiated by a black body is P and it radiates maximum energy at wavelength, λ0. If the temperature of the black body is now changed so that it radiates maximum energy at wavelength 34λ0 , the power radiated by it will increases by a factor of
10
Sep
The power radiated by a black body is P and it radiates maximum energy at wavelength, λ0. If the temperature of the black body is now changed so that it radiates maximum energy at wavelength 34λ0 , the power radiated by it will increases by a factor of The power radiated by a black body [...]
The plots of intensity versus wavelength for three black bodies at temperatures T1 ,T2 and T3 respectively are shown in fig. Their temperatures are such that:
10
Sep
The plots of intensity versus wavelength for three black bodies at temperatures T1 ,T2 and T3 respectively are shown in fig. Their temperatures are such that: T2 and T3 respectively are shown in fig. Their temperatures are such that: The plots of intensity versus wavelength for three black bodies at [...]
A black body is at a temperature of 2880 K. The energy of radiation emitted by this body with wavelength between 499 nm and 500 nm is U1, between 999 nm and 1000 nm, is U2 and between 1499 nm and 1500 nm is U3 . Wien’s constant, b = 2.88 × 10^6 nm−K. Then
10
Sep
A black body is at a temperature of 2880 K. The energy of radiation emitted by this body with wavelength between 499 nm and 500 nm is U1, between 999 nm and 1000 nm, is U2 and between 1499 nm and 1500 nm is U3 . Wien’s constant, b = 2.88 × 10^6 nm−K. Then [...]
A liquid in a beaker has temperature θ at time t and θ0 is temperature of surroundings, then according to Newton’s law of cooling, correct graph between loge (θ−θ 0 ) and t is :
10
Sep
A liquid in a beaker has temperature θ at time t and θ0 is temperature of surroundings, then according to Newton’s law of cooling, correct graph between loge (θ−θ 0 ) and t is : A liquid in a beaker has temperature θ at time t and θ0 is temperature of surroundings correct graph between [...]
A hot liquid is kept in a big room. Its temperature is plotted as a function of time. Which of the following curves may present the plot ?
10
Sep
A hot liquid is kept in a big room. Its temperature is plotted as a function of time. Which of the following curves may present the plot ? A hot liquid is kept in a big room. Its temperature is plotted as a function of time. Which of the following curves may present the plot [...]
A body cools from 50 C to 40 C in 5 min. The surrounding temperature is 20 C. In what further time (in min) will it cool to 30 C?
10
Sep
A body cools from 50 C to 40 C in 5 min. The surrounding temperature is 20 C. In what further time (in min) will it cool to 30 C? A body cools from 50 C to 40 C in 5 min. The surrounding temperature is 20 C. In what further time (in min) will [...]
The sun radiates energy in all directions. The average radiations received on the earth surface from the sun is 1.4 kilowatt/m^2. The average earth-sun distance is 1.5×10^11 meters. The mass lost by the sun per day is.
10
Sep
The sun radiates energy in all directions. The average radiations received on the earth surface from the sun is 1.4 kilowatt/m^2. The average earth-sun distance is 1.5×10^11 meters. The mass lost by the sun per day is. The temperature of an isolated black body falls from T1 to T2 in time t . Let c [...]
If the temperature of the sun were to increase from T to 2T and its radius from R to 2R, then the ratio of the radiant energy received on earth to what it was previously will be
10
Sep
If the temperature of the sun were to increase from T to 2T and its radius from R to 2R, then the ratio of the radiant energy received on earth to what it was previously will be If the temperature of the sun were to increase from T to 2T and its radius from R [...]