B The process of convection and conduction requires some medium for travelling of material particle for transmission of heat. In vacuum there is no material. So, heat travels in vacuum by radiation.
AIIMS-1998
Heat Transfer
149509
For athermanous substances, coefficient of transmission is
1 equal to one
2 zero
3 less than one but greater than zero
4 greater than one
Explanation:
B The substances which can not transmit the radiant heat incident upon their surfaces are called athermanous or diathermanous substances. For such substance, the value of the coefficient of transmission is zero.
MHT-CET 2020
Heat Transfer
149516
Kirchoff's law of radiation proves that a good emitter is a
1 bad absorber of heat
2 good absorber of heat
3 good reflector of heat
4 good transmitter of heat
Explanation:
B According to Kirchoff 's law a good emitter is a good absorber of heat. Explanation of it is that, when we give heat energy to a substance the molecules of that substance get excited due to excessive amount of energy inputs. Now, the good absorbers of heat energy will absorb great amount of heat energy which will make the molecules of that substance excited in more amounts. Now the molecules will surely want to expel that extra amount of energy to become a stable molecule. Now amount of heat energy will be directly proportional to the absorbed energy. That's why the substances which are good absorber are good emitters too.
MHT-CET 2020
Heat Transfer
149534
Absorption coefficient of an open window is :
1 1
2 0.25
3 zero
4 0.5
Explanation:
A Open window or open doors are behaves like a perfectly black body and absorption coefficient of a perfectly black body is one that's why absorption coefficient for open window will be one.
NEET Test Series from KOTA - 10 Papers In MS WORD
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Heat Transfer
149501
Heat travels through vacuum by:
1 convection
2 radiation
3 conduction
4 all of these
Explanation:
B The process of convection and conduction requires some medium for travelling of material particle for transmission of heat. In vacuum there is no material. So, heat travels in vacuum by radiation.
AIIMS-1998
Heat Transfer
149509
For athermanous substances, coefficient of transmission is
1 equal to one
2 zero
3 less than one but greater than zero
4 greater than one
Explanation:
B The substances which can not transmit the radiant heat incident upon their surfaces are called athermanous or diathermanous substances. For such substance, the value of the coefficient of transmission is zero.
MHT-CET 2020
Heat Transfer
149516
Kirchoff's law of radiation proves that a good emitter is a
1 bad absorber of heat
2 good absorber of heat
3 good reflector of heat
4 good transmitter of heat
Explanation:
B According to Kirchoff 's law a good emitter is a good absorber of heat. Explanation of it is that, when we give heat energy to a substance the molecules of that substance get excited due to excessive amount of energy inputs. Now, the good absorbers of heat energy will absorb great amount of heat energy which will make the molecules of that substance excited in more amounts. Now the molecules will surely want to expel that extra amount of energy to become a stable molecule. Now amount of heat energy will be directly proportional to the absorbed energy. That's why the substances which are good absorber are good emitters too.
MHT-CET 2020
Heat Transfer
149534
Absorption coefficient of an open window is :
1 1
2 0.25
3 zero
4 0.5
Explanation:
A Open window or open doors are behaves like a perfectly black body and absorption coefficient of a perfectly black body is one that's why absorption coefficient for open window will be one.
B The process of convection and conduction requires some medium for travelling of material particle for transmission of heat. In vacuum there is no material. So, heat travels in vacuum by radiation.
AIIMS-1998
Heat Transfer
149509
For athermanous substances, coefficient of transmission is
1 equal to one
2 zero
3 less than one but greater than zero
4 greater than one
Explanation:
B The substances which can not transmit the radiant heat incident upon their surfaces are called athermanous or diathermanous substances. For such substance, the value of the coefficient of transmission is zero.
MHT-CET 2020
Heat Transfer
149516
Kirchoff's law of radiation proves that a good emitter is a
1 bad absorber of heat
2 good absorber of heat
3 good reflector of heat
4 good transmitter of heat
Explanation:
B According to Kirchoff 's law a good emitter is a good absorber of heat. Explanation of it is that, when we give heat energy to a substance the molecules of that substance get excited due to excessive amount of energy inputs. Now, the good absorbers of heat energy will absorb great amount of heat energy which will make the molecules of that substance excited in more amounts. Now the molecules will surely want to expel that extra amount of energy to become a stable molecule. Now amount of heat energy will be directly proportional to the absorbed energy. That's why the substances which are good absorber are good emitters too.
MHT-CET 2020
Heat Transfer
149534
Absorption coefficient of an open window is :
1 1
2 0.25
3 zero
4 0.5
Explanation:
A Open window or open doors are behaves like a perfectly black body and absorption coefficient of a perfectly black body is one that's why absorption coefficient for open window will be one.
B The process of convection and conduction requires some medium for travelling of material particle for transmission of heat. In vacuum there is no material. So, heat travels in vacuum by radiation.
AIIMS-1998
Heat Transfer
149509
For athermanous substances, coefficient of transmission is
1 equal to one
2 zero
3 less than one but greater than zero
4 greater than one
Explanation:
B The substances which can not transmit the radiant heat incident upon their surfaces are called athermanous or diathermanous substances. For such substance, the value of the coefficient of transmission is zero.
MHT-CET 2020
Heat Transfer
149516
Kirchoff's law of radiation proves that a good emitter is a
1 bad absorber of heat
2 good absorber of heat
3 good reflector of heat
4 good transmitter of heat
Explanation:
B According to Kirchoff 's law a good emitter is a good absorber of heat. Explanation of it is that, when we give heat energy to a substance the molecules of that substance get excited due to excessive amount of energy inputs. Now, the good absorbers of heat energy will absorb great amount of heat energy which will make the molecules of that substance excited in more amounts. Now the molecules will surely want to expel that extra amount of energy to become a stable molecule. Now amount of heat energy will be directly proportional to the absorbed energy. That's why the substances which are good absorber are good emitters too.
MHT-CET 2020
Heat Transfer
149534
Absorption coefficient of an open window is :
1 1
2 0.25
3 zero
4 0.5
Explanation:
A Open window or open doors are behaves like a perfectly black body and absorption coefficient of a perfectly black body is one that's why absorption coefficient for open window will be one.