What mechanism at the microscopic level determines whether a system heats up or not?












2














When placed in an ordinary or a microwave oven, a beaker of water heats up except during boiling (i.e., a phase change involving latent heat). Now, suppose a system absorbs energy in such a way that the electrons are excited to higher energy levels. Will this necessarily heat up the system? In other words, is heating caused by the electrons or atoms in an object being excited to higher energy levels?






quantum-mechanics thermodynamics statistical-mechanics solid-state-physics phase-transition







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    2














    When placed in an ordinary or a microwave oven, a beaker of water heats up except during boiling (i.e., a phase change involving latent heat). Now, suppose a system absorbs energy in such a way that the electrons are excited to higher energy levels. Will this necessarily heat up the system? In other words, is heating caused by the electrons or atoms in an object being excited to higher energy levels?






    quantum-mechanics thermodynamics statistical-mechanics solid-state-physics phase-transition







    share|cite|improve this question



























      2












      2








      2







      When placed in an ordinary or a microwave oven, a beaker of water heats up except during boiling (i.e., a phase change involving latent heat). Now, suppose a system absorbs energy in such a way that the electrons are excited to higher energy levels. Will this necessarily heat up the system? In other words, is heating caused by the electrons or atoms in an object being excited to higher energy levels?






      quantum-mechanics thermodynamics statistical-mechanics solid-state-physics phase-transition







      share|cite|improve this question















      When placed in an ordinary or a microwave oven, a beaker of water heats up except during boiling (i.e., a phase change involving latent heat). Now, suppose a system absorbs energy in such a way that the electrons are excited to higher energy levels. Will this necessarily heat up the system? In other words, is heating caused by the electrons or atoms in an object being excited to higher energy levels?






      quantum-mechanics thermodynamics statistical-mechanics solid-state-physics phase-transition




      quantum-mechanics thermodynamics statistical-mechanics solid-state-physics phase-transition






      share|cite|improve this question















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      edited 31 mins ago









      Geoffrey

      3,64911229




      3,64911229










      asked 5 hours ago









      mithusengupta123

      1,30811334




      1,30811334






















          3 Answers
          3






          active

          oldest

          votes


















          1














          On the case of a microwave oven the water molecules in the food are made to vibrate. Water molecules are tiny electric dipoles and these are made to vibrate more strongly. The molecules stay in the electronic ground state.






          share|cite|improve this answer























          • What happens in ordinary ovens/burners? For heating to take place, a necessary condition is that the system must absorb energy. For this to happen, there must be a coupling between the environment that supplies energy and the system that absorbs it. For the microwave example, it is the electromagnetic microwave that couples to the dipole moment of water molecules.
            – mithusengupta123
            3 hours ago










          • The microwave photon energy level causes rotation not vibration of water dipole molecules. The vibration energy is higher than the microwave oven photon energy. For a good explanation of the interaction of radiation with matter, check out the Hyperphysics web site
            – Bob D
            3 hours ago





















          1














          The microwave photon energy level gives rotational kinetic energy to water molecules due to interaction of the electromagnetic field with the water dipole molecule. The rotational kinetic energy is subsequently randomized to increase the average translational kinetic energy of the molecules, increasing the temperature of the water molecules. The microwave energy levels are well below those needed to excite electrons to higher levels.



          A regular oven cooks with infrared electromagnetic energy. The photon energy level corresponds to molecular vibration. These energy levels are likewise too low for electron excitation.



          Hope this helps






          share|cite|improve this answer





















          • A toaster oven certainly uses radiation, but I'd argue that a bake-a-cake oven also uses conduction and convection.
            – psitae
            26 mins ago



















          0














          The heat contained in a system can be thought of as the total kinetic energy of a system. my2cts' answer is correct, but I'll add that if you excite an electron to a higher energy level, that will indeed cause heating in many cases (see for example FRET).



          The friction between the water molecules and the rest of the system is what causes things to heat up in a microwave. In a conventional oven, it's a direct transfer of kinetic energy from hot air.



          Homework question: would something heat up in a microwave if it didn't contain any water?






          share|cite|improve this answer





















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            3 Answers
            3






            active

            oldest

            votes








            3 Answers
            3






            active

            oldest

            votes









            active

            oldest

            votes






            active

            oldest

            votes









            1














            On the case of a microwave oven the water molecules in the food are made to vibrate. Water molecules are tiny electric dipoles and these are made to vibrate more strongly. The molecules stay in the electronic ground state.






            share|cite|improve this answer























            • What happens in ordinary ovens/burners? For heating to take place, a necessary condition is that the system must absorb energy. For this to happen, there must be a coupling between the environment that supplies energy and the system that absorbs it. For the microwave example, it is the electromagnetic microwave that couples to the dipole moment of water molecules.
              – mithusengupta123
              3 hours ago










            • The microwave photon energy level causes rotation not vibration of water dipole molecules. The vibration energy is higher than the microwave oven photon energy. For a good explanation of the interaction of radiation with matter, check out the Hyperphysics web site
              – Bob D
              3 hours ago


















            1














            On the case of a microwave oven the water molecules in the food are made to vibrate. Water molecules are tiny electric dipoles and these are made to vibrate more strongly. The molecules stay in the electronic ground state.






            share|cite|improve this answer























            • What happens in ordinary ovens/burners? For heating to take place, a necessary condition is that the system must absorb energy. For this to happen, there must be a coupling between the environment that supplies energy and the system that absorbs it. For the microwave example, it is the electromagnetic microwave that couples to the dipole moment of water molecules.
              – mithusengupta123
              3 hours ago










            • The microwave photon energy level causes rotation not vibration of water dipole molecules. The vibration energy is higher than the microwave oven photon energy. For a good explanation of the interaction of radiation with matter, check out the Hyperphysics web site
              – Bob D
              3 hours ago
















            1












            1








            1






            On the case of a microwave oven the water molecules in the food are made to vibrate. Water molecules are tiny electric dipoles and these are made to vibrate more strongly. The molecules stay in the electronic ground state.






            share|cite|improve this answer














            On the case of a microwave oven the water molecules in the food are made to vibrate. Water molecules are tiny electric dipoles and these are made to vibrate more strongly. The molecules stay in the electronic ground state.







            share|cite|improve this answer














            share|cite|improve this answer



            share|cite|improve this answer








            edited 3 hours ago

























            answered 4 hours ago









            my2cts

            4,4082617




            4,4082617












            • What happens in ordinary ovens/burners? For heating to take place, a necessary condition is that the system must absorb energy. For this to happen, there must be a coupling between the environment that supplies energy and the system that absorbs it. For the microwave example, it is the electromagnetic microwave that couples to the dipole moment of water molecules.
              – mithusengupta123
              3 hours ago










            • The microwave photon energy level causes rotation not vibration of water dipole molecules. The vibration energy is higher than the microwave oven photon energy. For a good explanation of the interaction of radiation with matter, check out the Hyperphysics web site
              – Bob D
              3 hours ago




















            • What happens in ordinary ovens/burners? For heating to take place, a necessary condition is that the system must absorb energy. For this to happen, there must be a coupling between the environment that supplies energy and the system that absorbs it. For the microwave example, it is the electromagnetic microwave that couples to the dipole moment of water molecules.
              – mithusengupta123
              3 hours ago










            • The microwave photon energy level causes rotation not vibration of water dipole molecules. The vibration energy is higher than the microwave oven photon energy. For a good explanation of the interaction of radiation with matter, check out the Hyperphysics web site
              – Bob D
              3 hours ago


















            What happens in ordinary ovens/burners? For heating to take place, a necessary condition is that the system must absorb energy. For this to happen, there must be a coupling between the environment that supplies energy and the system that absorbs it. For the microwave example, it is the electromagnetic microwave that couples to the dipole moment of water molecules.
            – mithusengupta123
            3 hours ago




            What happens in ordinary ovens/burners? For heating to take place, a necessary condition is that the system must absorb energy. For this to happen, there must be a coupling between the environment that supplies energy and the system that absorbs it. For the microwave example, it is the electromagnetic microwave that couples to the dipole moment of water molecules.
            – mithusengupta123
            3 hours ago












            The microwave photon energy level causes rotation not vibration of water dipole molecules. The vibration energy is higher than the microwave oven photon energy. For a good explanation of the interaction of radiation with matter, check out the Hyperphysics web site
            – Bob D
            3 hours ago






            The microwave photon energy level causes rotation not vibration of water dipole molecules. The vibration energy is higher than the microwave oven photon energy. For a good explanation of the interaction of radiation with matter, check out the Hyperphysics web site
            – Bob D
            3 hours ago













            1














            The microwave photon energy level gives rotational kinetic energy to water molecules due to interaction of the electromagnetic field with the water dipole molecule. The rotational kinetic energy is subsequently randomized to increase the average translational kinetic energy of the molecules, increasing the temperature of the water molecules. The microwave energy levels are well below those needed to excite electrons to higher levels.



            A regular oven cooks with infrared electromagnetic energy. The photon energy level corresponds to molecular vibration. These energy levels are likewise too low for electron excitation.



            Hope this helps






            share|cite|improve this answer





















            • A toaster oven certainly uses radiation, but I'd argue that a bake-a-cake oven also uses conduction and convection.
              – psitae
              26 mins ago
















            1














            The microwave photon energy level gives rotational kinetic energy to water molecules due to interaction of the electromagnetic field with the water dipole molecule. The rotational kinetic energy is subsequently randomized to increase the average translational kinetic energy of the molecules, increasing the temperature of the water molecules. The microwave energy levels are well below those needed to excite electrons to higher levels.



            A regular oven cooks with infrared electromagnetic energy. The photon energy level corresponds to molecular vibration. These energy levels are likewise too low for electron excitation.



            Hope this helps






            share|cite|improve this answer





















            • A toaster oven certainly uses radiation, but I'd argue that a bake-a-cake oven also uses conduction and convection.
              – psitae
              26 mins ago














            1












            1








            1






            The microwave photon energy level gives rotational kinetic energy to water molecules due to interaction of the electromagnetic field with the water dipole molecule. The rotational kinetic energy is subsequently randomized to increase the average translational kinetic energy of the molecules, increasing the temperature of the water molecules. The microwave energy levels are well below those needed to excite electrons to higher levels.



            A regular oven cooks with infrared electromagnetic energy. The photon energy level corresponds to molecular vibration. These energy levels are likewise too low for electron excitation.



            Hope this helps






            share|cite|improve this answer












            The microwave photon energy level gives rotational kinetic energy to water molecules due to interaction of the electromagnetic field with the water dipole molecule. The rotational kinetic energy is subsequently randomized to increase the average translational kinetic energy of the molecules, increasing the temperature of the water molecules. The microwave energy levels are well below those needed to excite electrons to higher levels.



            A regular oven cooks with infrared electromagnetic energy. The photon energy level corresponds to molecular vibration. These energy levels are likewise too low for electron excitation.



            Hope this helps







            share|cite|improve this answer












            share|cite|improve this answer



            share|cite|improve this answer










            answered 2 hours ago









            Bob D

            1,992211




            1,992211












            • A toaster oven certainly uses radiation, but I'd argue that a bake-a-cake oven also uses conduction and convection.
              – psitae
              26 mins ago


















            • A toaster oven certainly uses radiation, but I'd argue that a bake-a-cake oven also uses conduction and convection.
              – psitae
              26 mins ago
















            A toaster oven certainly uses radiation, but I'd argue that a bake-a-cake oven also uses conduction and convection.
            – psitae
            26 mins ago




            A toaster oven certainly uses radiation, but I'd argue that a bake-a-cake oven also uses conduction and convection.
            – psitae
            26 mins ago











            0














            The heat contained in a system can be thought of as the total kinetic energy of a system. my2cts' answer is correct, but I'll add that if you excite an electron to a higher energy level, that will indeed cause heating in many cases (see for example FRET).



            The friction between the water molecules and the rest of the system is what causes things to heat up in a microwave. In a conventional oven, it's a direct transfer of kinetic energy from hot air.



            Homework question: would something heat up in a microwave if it didn't contain any water?






            share|cite|improve this answer


























              0














              The heat contained in a system can be thought of as the total kinetic energy of a system. my2cts' answer is correct, but I'll add that if you excite an electron to a higher energy level, that will indeed cause heating in many cases (see for example FRET).



              The friction between the water molecules and the rest of the system is what causes things to heat up in a microwave. In a conventional oven, it's a direct transfer of kinetic energy from hot air.



              Homework question: would something heat up in a microwave if it didn't contain any water?






              share|cite|improve this answer
























                0












                0








                0






                The heat contained in a system can be thought of as the total kinetic energy of a system. my2cts' answer is correct, but I'll add that if you excite an electron to a higher energy level, that will indeed cause heating in many cases (see for example FRET).



                The friction between the water molecules and the rest of the system is what causes things to heat up in a microwave. In a conventional oven, it's a direct transfer of kinetic energy from hot air.



                Homework question: would something heat up in a microwave if it didn't contain any water?






                share|cite|improve this answer












                The heat contained in a system can be thought of as the total kinetic energy of a system. my2cts' answer is correct, but I'll add that if you excite an electron to a higher energy level, that will indeed cause heating in many cases (see for example FRET).



                The friction between the water molecules and the rest of the system is what causes things to heat up in a microwave. In a conventional oven, it's a direct transfer of kinetic energy from hot air.



                Homework question: would something heat up in a microwave if it didn't contain any water?







                share|cite|improve this answer












                share|cite|improve this answer



                share|cite|improve this answer










                answered 3 hours ago









                psitae

                613522




                613522






























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