isothermal expansion

Isothermal expansion occurs when a gas expands (increases in volume) while its temperature remains constant. During this process, the gas does work by pushing against its surroundings, such as a piston moving outward. To keep the temperature steady, heat from outside sources enters the gas, balancing the energy used for work. Since temperature stays the same, the internal energy of the gas doesn't change. This process highlights a balance where energy input as heat exactly matches the energy the gas uses to expand, ensuring the temperature remains constant throughout.