# Understanding Energy Transfer: Thermodynamics in an Insulated Box Scenario

• cragar
In summary, the temperature of an insulated box will go up when energy is pumped into it, but this is similar to the Raman effect where light is scattered and leaves the system with higher energy than the light that entered.
cragar
Let's say we have an insulated box with a refrigerator in it.
Now the fridge is plugged in from outside. The box is perfectly insulated.
The door of the fridge is open. What happens to the temperate inside the box.
their is air in the fridge. I was told that the temperature of the box will go up because we are pumping energy into it.
But then I thought of laser cooling. When laser cooling happens we shoot photons into
a cloud of atoms and they Doppler shift the light an absorb them and slow down.
We pumped energy into that system and it cooled down.
Is it always true that if I pump energy into a system that it will heat up.

Yes, it is always true that if you pump heat energy in (or input electrical energy and immediately convert it to heat), it will heat up. That's basically the definition of "heat up".

ok but in laser cooling we pump in energy and it cools down.

If you cool something, something else must heat up. Laser cooling is mostly used to cool at atom level. I don't find it plausible that this is some kind of optical trapping of the atoms - forcing them to stop viberating. Laser cooling is however mostly used in quantum physics so I can't help you further regarding what heats up if the atoms cools down. At least the laser equipment itself heats up - that for sure :-)

Vidar

In laser cooling, the laser light gets scattered and leaves the system with higher energy than the light that entered. So there is no net pumping of energy but energy removal.

so the light gets absorbed and then remitted with more energy so it took energy away from the atom. is this similar to the Raman effect.

If you ran the laser cooler in an opaque box, where the photons could not leave,
the inside of the box would heat up as well.

## 1. What is thermodynamics?

Thermodynamics is the branch of science that deals with the relationships between heat, energy, and work. It studies how energy is transferred between different forms and how it affects physical systems.

## 2. What are the laws of thermodynamics?

The first law of thermodynamics states that energy cannot be created or destroyed, only transferred or converted from one form to another. The second law states that the total entropy (disorder) of a closed system will always increase over time. The third law states that the entropy of a perfectly ordered crystal at absolute zero temperature is zero.

## 3. How is thermodynamics applied in real-life situations?

Thermodynamics has many practical applications, such as in the design of engines, refrigeration systems, and power plants. It is also used in studying weather and climate, chemical reactions, and the behavior of materials at different temperatures and pressures.

## 4. What is the difference between heat and temperature in thermodynamics?

Heat is the transfer of energy from a hotter object to a cooler one. Temperature is a measure of the average kinetic energy of the molecules in a substance. In thermodynamics, temperature is used to quantify the direction and amount of heat transfer.

## 5. What are the three modes of heat transfer?

The three modes of heat transfer are conduction, convection, and radiation. Conduction is the transfer of heat through a solid or between two objects in contact. Convection is the transfer of heat through a fluid (gas or liquid) due to its movement. Radiation is the transfer of heat through electromagnetic waves, such as infrared radiation from the sun.

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