Provost Theory of Exchange

Q. Which of the following statements is incorrect with regard to Prevost's theory of heat exchange?

1. All bodies absorb as well as emit thermal radiations at all temperatures greater than absolute zero.
2. If the amount of radiation absorbed by a body is equal to that emitted by the body, then the body will be in thermal equilibrium.
3. The process of heat exchange among bodies is a continuous phenomena.
4. The heat exchange occurs at absolute zero temperature as well.

Q.

The figure here shows four paths on a p-V diagrams along which as gas can be taken from state i to state f. Rank the paths according to the magnitude of the energy transferred as heat Q between the gas and its environment, greatest first

1. 1 > 2 > 3 > 4

2. 4 > 3 > 2 > 1

3. 1 = 2 = 3 = 4

4. Need more information

Q. The room temperature is ${25}^{\circ }C$.A body cools from ${60}^{\circ }Cto{50}^{\circ }C$ in 10 minutes. Assuming Newton’s Law of cooling to hold good, the temperature of the body at the end of next 10 minutes will be

1. ${40}^{\circ }C$
2. $42.{85}^{\circ }C$
3. $45.{75}^{\circ }C$
4. $38.{85}^{\circ }C$

Q. Which of the following statements is incorrect with regard to Prevost's theory of heat exchange?

1. All bodies absorb as well as emit thermal radiations at all temperatures greater than absolute zero.
2. If the amount of radiation absorbed by a body is equal to that emitted by the body, then the body will be in thermal equilibrium.
3. The process of heat exchange among bodies is a continuous phenomena.
4. The heat exchange occurs at absolute zero temperature as well.

Q. A hot body placed in a surrounding of temperature ${\theta }_0$ obeys newton's law of cooling $\frac{d\theta }{dt}=k(\theta -{\theta }_0)$ its temperature at t= 0 is ${\theta }_1$ . the specific heat capacity of the body s and its mass is m. find (a) the maximum heat that the body can lose and (b) the time starting from $t=0$ in which it will lose 90% of this maximum heat.

Q. The amount of radiation emitted per second is independent of surrounding conditions.

1. False
2. True

Q. The temperature of a blackbody radiation enclosed in a container of volume $V$ is increased from ${100}^{o}C$ to ${1000}^{o}C$. The heat required in the process is

1. $9.21\times {10}^{-5}$ cal
2. $2.17\times {10}^{-4}$ cal
3. $4.79\times {10}^{-4}$ cal
4. $7.54\times {10}^{-4}$ cal
5. Information not sufficient

Q. A body with an initial temperature ${\theta }_1$ is allowed to cool in surrounding which is at a constant temperature of ${\theta }_0({\theta }_0<{\theta }_1)$, Assume that Newton's law of cooling is obeyed. Let $k=constant$. The temperature of the body after time $t$ is best expressed by

1. $({\theta }_1-{\theta }_0)ln\left(kt\right)$
2. $({\theta }_1-{\theta }_0)e^{kt}$
3. ${\theta }_1{e}^{-kt}-{\theta }_0$
4. $({\theta }_0+({\theta }_1-{\theta }_0\left)e^{-kt}\right)$

Q. A body in a laboratory takes 4 minutes to cool from ${61}^{o}C$ and ${59}^{o}C$. If the laboratory temperature is ${30}^{o}C$ then the time taken by it to cool from ${51}^{o}C$ to ${49}^{o}C$ will be:

1. 6 min
2. 4 min
3. 5 min
4. 8 min

Q. The amount of radiation emitted per second is independent of surrounding conditions.

1. False
2. True

Q.

A hot body placed in a surrounding of temperature ${\theta }_0$, obeys Newton's law of cooling $\frac{d\theta }{dt}=-k(\theta -{\theta }_0)$. Its temperature at t = 0 is ${\theta }_1$. The specific heat capacity of the body is s and its mass is m. Find (a) the maximum heat that the body can lose and (b) the time starting from t=0 in which it will lose 90% of this maximum heat.

Q. A hot body is placed in cold surroundings. Its rate of cooling is $3^o$C per minute when its temperature is ${70}^o$C and ${1.5}^o$C per minute when its temperature is ${50}^o$C. Its rate of cooling when temperature is ${40}^o$C is

1. 0.25${}^o$C/min
2. 0.5${}^o$C/min
3. 0.75${}^o$C/min
4. 1${}^o$C/min

Q. Experimental investigations show that the intensity of solar radiation is maximum for a wavelength $480$ nm in the visible region. Estimate the surface temperature of sun. (Given Wien's constant $b=2.88\times {10}^{-3}mK.$)

1. $4000K$
2. $6000K$
3. $8000K$
4. ${10}^{6}K$

Q. Which of the following statements is incorrect with regard to Prevost's theory of heat exchange?

1. All bodies absorb as well as emit thermal radiations at all temperatures greater than absolute zero.
2. If the amount of radiation absorbed by a body is equal to that emitted by the body, then the body will be in thermal equilibrium.
3. The process of heat exchange among bodies is a continuous phenomena.
4. The heat exchange occurs at absolute zero temperature as well.

Q. If the sun become twice hotter, it will radiate

1. Predominantly in the infrared
2. Energy sixteen times larger
3. Energy sixteen times smaller
4. Predominantly in the ultra violet

Q. Corresponding to a given temperature, there is a wavelength ${\lambda }_m$, for which the intensity of heat radiations is

1. maximum
2. constant
3. zero
4. minimum

Q. Assertion :According to Newton's law of cooling the rate of loss of heat , $-dQ/dt$ of the body is directly proportional to the difference of temperature. Reason: This law holds for all type of temperature differences

1. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
2. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
3. Assertion is correct but Reason is incorrect
4. Both Assertion and Reason are incorrect

Q. A body with an initial temperature ${\theta }_i$, is allowed to cool in surrounding which is at a constant temperature of ${\theta }_0$ $({\theta }_0<{\theta }_1)$. Assume that Newton's law of cooling is obeyed. Let $K$ = constant. The temperature of the body after time $t$ is best expressed by

1. $({\theta }_i-{\theta }_0)e^{-Kt}$
2. $({\theta }_i<{\theta }_0)ln\left(kt\right)$
3. ${\theta }_0+({\theta }_i-{\theta }_0)e^{-Kt}$
4. ${\theta }_i{e}^{-Kt}-{\theta }_0$

Q. Two bodies have thermal capacities in the ratio 3 : 4 and the rates of loss of heat in the ratio 3 : 5. Their rates of cooling will be in the ratio of :

1. 9 : 20
2. 4 : 5
3. 5 : 4
4. 1 : 1

Q. What is the value of ${\theta }_1$, the temperature of junction $B$?

1. ${40.4}^o$C
2. ${30.4}^o$C
3. ${70.9}^o$C
4. ${50.4}^o$C

Q. Pervost's theory of heat exchange is not applicable at temperature

1. $0^{o}R$
2. $0^{o}C$
3. $0K$
4. $0^{o}F$

Q. According to Newton's law of cooling, the rate of cooling of a body is proportional to $(\Delta \theta {)}^n$ where $\Delta \theta$ is the difference of temperature of body and the surrounding and n is equal to :

1. 4
2. 1
3. 2
4. 3

Q. The amount of radiation emitted per second is independent of surrounding conditions.

1. False
2. True