# Why Does Electrical Work Cause Changes in the Internal Energy of a System?

• Dario56
In summary, the conversation discusses the first law of thermodynamics and its application to galvanic cells. It explains that in galvanic cells, electrical work is negative and decreases the internal energy of the system. The connection between electrical work and internal energy is that the work done by the electric field in the system decreases the total microscopic kinetic and potential energy of the molecules and atoms. This is similar to the process in a capacitor or condenser, where accumulated charges decrease by doing work in the circuit and returning to the opposite plate, resulting in a decrease in internal energy.
Dario56
TL;DR Summary
What does work done by electric field have to do with internal energy of the system? Why does electrical work cause changes in internal energy of the system?
If we look at system at constant temperature and volume which is galvanic cell, first law of thermodynamics states: $$dU = dQ + dW'$$

Where W' is electrical work done by galvanic cell and Q is heat exchanged with surroundings.

As far as I know electrical work is work done by electric field when charge moves between certain potential difference. In galvanic cell, potential difference exists between two electrodes.

Internal energy is sum of total microscopic kinetic energy of all molecules and atoms and their potential energy of interaction (energy stored in intermolecular and chemical bonds).

What does work done by electric field have to do with internal energy of the system? Why does electrical work cause changes in internal energy of the system?

In galvanic cells, electrical work is negative as work is done by the system and from the first law it tends to decrease internal energy of the system.

I can't really see the connection between work done by electric field in the galvanic cell and sum of microscopic kinetic energy and microscopic potential energy of interaction.

Instead of chemical buttery let us see capacitor or condenser. Accumulated charges decrease by doing works in circuit and come back to opposite plate. Thus decreased charge means decreased internal energy. Though I am not well aware of chemistry I assume similar process is going in battery.

## 1. Why does electrical work cause changes in the internal energy of a system?

Electrical work involves the transfer of energy in the form of electric current. When this current flows through a system, it causes the movement of charged particles, which in turn leads to changes in the internal energy of the system. This is because the movement of charged particles generates heat, which is a form of energy, and this heat increases the overall internal energy of the system.

## 2. How does electrical work affect the temperature of a system?

When electrical work is done on a system, it increases the internal energy of the system, which in turn leads to an increase in temperature. This is because the movement of charged particles generates heat, which raises the average kinetic energy of the particles in the system, resulting in a higher temperature.

## 3. Can electrical work cause a decrease in the internal energy of a system?

Yes, electrical work can cause a decrease in the internal energy of a system. This can happen when the electrical work is used to power a device that performs work on the system, such as a refrigerator. In this case, the electrical work is converted into mechanical work, which decreases the internal energy of the system.

## 4. What factors can affect the amount of electrical work required to change the internal energy of a system?

The amount of electrical work required to change the internal energy of a system depends on several factors, including the resistance of the system, the amount of current flowing through it, and the duration of the work. Other factors that can affect the amount of electrical work include the type of material the system is made of and any external forces acting on the system.

## 5. How is the concept of electrical work related to the laws of thermodynamics?

The concept of electrical work is closely related to the first and second laws of thermodynamics. The first law states that energy cannot be created or destroyed, only transferred or converted from one form to another. This means that the electrical work done on a system will result in a corresponding increase in the internal energy of the system. The second law states that the total entropy of a closed system will always increase over time, which means that some energy will always be lost as heat during the process of electrical work.

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