149536
Wien's displacement law for emission of radiation can be written as
1 $\lambda_{\max }$ is proportional to absolute temperature $(\mathrm{T})$.
2 $\lambda_{\max }$ is proportional to square of absolute temperature (T).
3 $\lambda_{\max }$ is inversely proportional to absolute temperature $(\mathrm{T})$.
4 $\lambda_{\max }$ is inversely proportional to square of absolute temperature $(\mathrm{T})$. $\left(\lambda_{\max }=\right.$ wavelength whose energy density is greatest)
Explanation:
C Wein's displacement law states that, $\lambda_{\mathrm{m}} \mathrm{T}=\mathrm{b} \text { (constant) }$ or $\lambda_{\mathrm{m}} \propto \frac{1}{\mathrm{~T}}$ It shows that $\lambda_{\max }$ is inversely proportional to absolute temperature.
J and K CET- 2008
Heat Transfer
149537
The temperature at which a black body ceases to radiate energy, is
1 $0 \mathrm{~K}$
2 $273 \mathrm{~K}$
3 $30 \mathrm{~K}$
4 $400 \mathrm{~K}$
Explanation:
A From the Stefan's law rate of energy emitted $\frac{\mathrm{dQ}}{\mathrm{dt}} \propto \mathrm{T}^{4}$ Thus at $0 \mathrm{~K}, \frac{\mathrm{dQ}}{\mathrm{dt}}=0$ at $0 \mathrm{~K}$, no heat is emitted.
J and K CET- 2007
Heat Transfer
149548
A black body
1 has an emissivity of zero
2 is the most efficient absorber
3 is the least efficient emitter
4 has the same emission spectrum at all temperatures
Explanation:
B Characteristics of black body (i) A perfectly black body absorbs all the radiant heat incident upon it. (ii) The coefficient of absorption for it is unity. (iii) Due to the blackness of such body it does not reflects any part of heat incident upon it.
J and K CET- 1997
Heat Transfer
149554
A black body is at $727^{\circ} \mathrm{C}$. It emits energy at a rate proportional to fourth power of an absolute temperature (T). Which of the following is the value of $T$ ?
1 $1454 \mathrm{~K}$
2 $727 \mathrm{~K}$
3 $1000 \mathrm{~K}$
4 $100 \mathrm{~K}$
Explanation:
C Amount of heat energy radiated per second by unit area of a black body is directly proportional to fourth power of absolute temperature. $E=\sigma T^{4}$ $\therefore \quad E \propto(727+273)^{4}$ $E \propto(1000)^{4}$
149536
Wien's displacement law for emission of radiation can be written as
1 $\lambda_{\max }$ is proportional to absolute temperature $(\mathrm{T})$.
2 $\lambda_{\max }$ is proportional to square of absolute temperature (T).
3 $\lambda_{\max }$ is inversely proportional to absolute temperature $(\mathrm{T})$.
4 $\lambda_{\max }$ is inversely proportional to square of absolute temperature $(\mathrm{T})$. $\left(\lambda_{\max }=\right.$ wavelength whose energy density is greatest)
Explanation:
C Wein's displacement law states that, $\lambda_{\mathrm{m}} \mathrm{T}=\mathrm{b} \text { (constant) }$ or $\lambda_{\mathrm{m}} \propto \frac{1}{\mathrm{~T}}$ It shows that $\lambda_{\max }$ is inversely proportional to absolute temperature.
J and K CET- 2008
Heat Transfer
149537
The temperature at which a black body ceases to radiate energy, is
1 $0 \mathrm{~K}$
2 $273 \mathrm{~K}$
3 $30 \mathrm{~K}$
4 $400 \mathrm{~K}$
Explanation:
A From the Stefan's law rate of energy emitted $\frac{\mathrm{dQ}}{\mathrm{dt}} \propto \mathrm{T}^{4}$ Thus at $0 \mathrm{~K}, \frac{\mathrm{dQ}}{\mathrm{dt}}=0$ at $0 \mathrm{~K}$, no heat is emitted.
J and K CET- 2007
Heat Transfer
149548
A black body
1 has an emissivity of zero
2 is the most efficient absorber
3 is the least efficient emitter
4 has the same emission spectrum at all temperatures
Explanation:
B Characteristics of black body (i) A perfectly black body absorbs all the radiant heat incident upon it. (ii) The coefficient of absorption for it is unity. (iii) Due to the blackness of such body it does not reflects any part of heat incident upon it.
J and K CET- 1997
Heat Transfer
149554
A black body is at $727^{\circ} \mathrm{C}$. It emits energy at a rate proportional to fourth power of an absolute temperature (T). Which of the following is the value of $T$ ?
1 $1454 \mathrm{~K}$
2 $727 \mathrm{~K}$
3 $1000 \mathrm{~K}$
4 $100 \mathrm{~K}$
Explanation:
C Amount of heat energy radiated per second by unit area of a black body is directly proportional to fourth power of absolute temperature. $E=\sigma T^{4}$ $\therefore \quad E \propto(727+273)^{4}$ $E \propto(1000)^{4}$
149536
Wien's displacement law for emission of radiation can be written as
1 $\lambda_{\max }$ is proportional to absolute temperature $(\mathrm{T})$.
2 $\lambda_{\max }$ is proportional to square of absolute temperature (T).
3 $\lambda_{\max }$ is inversely proportional to absolute temperature $(\mathrm{T})$.
4 $\lambda_{\max }$ is inversely proportional to square of absolute temperature $(\mathrm{T})$. $\left(\lambda_{\max }=\right.$ wavelength whose energy density is greatest)
Explanation:
C Wein's displacement law states that, $\lambda_{\mathrm{m}} \mathrm{T}=\mathrm{b} \text { (constant) }$ or $\lambda_{\mathrm{m}} \propto \frac{1}{\mathrm{~T}}$ It shows that $\lambda_{\max }$ is inversely proportional to absolute temperature.
J and K CET- 2008
Heat Transfer
149537
The temperature at which a black body ceases to radiate energy, is
1 $0 \mathrm{~K}$
2 $273 \mathrm{~K}$
3 $30 \mathrm{~K}$
4 $400 \mathrm{~K}$
Explanation:
A From the Stefan's law rate of energy emitted $\frac{\mathrm{dQ}}{\mathrm{dt}} \propto \mathrm{T}^{4}$ Thus at $0 \mathrm{~K}, \frac{\mathrm{dQ}}{\mathrm{dt}}=0$ at $0 \mathrm{~K}$, no heat is emitted.
J and K CET- 2007
Heat Transfer
149548
A black body
1 has an emissivity of zero
2 is the most efficient absorber
3 is the least efficient emitter
4 has the same emission spectrum at all temperatures
Explanation:
B Characteristics of black body (i) A perfectly black body absorbs all the radiant heat incident upon it. (ii) The coefficient of absorption for it is unity. (iii) Due to the blackness of such body it does not reflects any part of heat incident upon it.
J and K CET- 1997
Heat Transfer
149554
A black body is at $727^{\circ} \mathrm{C}$. It emits energy at a rate proportional to fourth power of an absolute temperature (T). Which of the following is the value of $T$ ?
1 $1454 \mathrm{~K}$
2 $727 \mathrm{~K}$
3 $1000 \mathrm{~K}$
4 $100 \mathrm{~K}$
Explanation:
C Amount of heat energy radiated per second by unit area of a black body is directly proportional to fourth power of absolute temperature. $E=\sigma T^{4}$ $\therefore \quad E \propto(727+273)^{4}$ $E \propto(1000)^{4}$
149536
Wien's displacement law for emission of radiation can be written as
1 $\lambda_{\max }$ is proportional to absolute temperature $(\mathrm{T})$.
2 $\lambda_{\max }$ is proportional to square of absolute temperature (T).
3 $\lambda_{\max }$ is inversely proportional to absolute temperature $(\mathrm{T})$.
4 $\lambda_{\max }$ is inversely proportional to square of absolute temperature $(\mathrm{T})$. $\left(\lambda_{\max }=\right.$ wavelength whose energy density is greatest)
Explanation:
C Wein's displacement law states that, $\lambda_{\mathrm{m}} \mathrm{T}=\mathrm{b} \text { (constant) }$ or $\lambda_{\mathrm{m}} \propto \frac{1}{\mathrm{~T}}$ It shows that $\lambda_{\max }$ is inversely proportional to absolute temperature.
J and K CET- 2008
Heat Transfer
149537
The temperature at which a black body ceases to radiate energy, is
1 $0 \mathrm{~K}$
2 $273 \mathrm{~K}$
3 $30 \mathrm{~K}$
4 $400 \mathrm{~K}$
Explanation:
A From the Stefan's law rate of energy emitted $\frac{\mathrm{dQ}}{\mathrm{dt}} \propto \mathrm{T}^{4}$ Thus at $0 \mathrm{~K}, \frac{\mathrm{dQ}}{\mathrm{dt}}=0$ at $0 \mathrm{~K}$, no heat is emitted.
J and K CET- 2007
Heat Transfer
149548
A black body
1 has an emissivity of zero
2 is the most efficient absorber
3 is the least efficient emitter
4 has the same emission spectrum at all temperatures
Explanation:
B Characteristics of black body (i) A perfectly black body absorbs all the radiant heat incident upon it. (ii) The coefficient of absorption for it is unity. (iii) Due to the blackness of such body it does not reflects any part of heat incident upon it.
J and K CET- 1997
Heat Transfer
149554
A black body is at $727^{\circ} \mathrm{C}$. It emits energy at a rate proportional to fourth power of an absolute temperature (T). Which of the following is the value of $T$ ?
1 $1454 \mathrm{~K}$
2 $727 \mathrm{~K}$
3 $1000 \mathrm{~K}$
4 $100 \mathrm{~K}$
Explanation:
C Amount of heat energy radiated per second by unit area of a black body is directly proportional to fourth power of absolute temperature. $E=\sigma T^{4}$ $\therefore \quad E \propto(727+273)^{4}$ $E \propto(1000)^{4}$
