Which cycle process has constant temperature?

Which cycle process has constant temperature?

• A. Isothermal Process
• B. Isobaric Process
• C. Isochoric Process
• D. Adiabatic Process

Answer: (A)

Constant temperature means the process is isothermal. For an ideal gas, temperature staying fixed means the internal energy, which depends only on temperature, does not change (dU = n Cv dT = 0). With T constant, heat added or removed goes entirely into or out of the system as work, so Q = W and the energy balance supports T staying the same. In an isothermal process, the relationship PV = nRT holds with T constant, so pressure and volume adjust inversely to keep their product constant (P ∝ 1/V). This contrasts with the other processes: when pressure is held constant, temperature typically changes as volume changes (T = PV/(nR) with P fixed). When volume is fixed, heat transfer changes temperature since no work is done (W = 0). In an adiabatic process, no heat is exchanged, so temperature changes as the gas expands or compresses, following relations like PV^γ = constant or TV^{γ−1} = constant.

Constant temperature means the process is isothermal. For an ideal gas, temperature staying fixed means the internal energy, which depends only on temperature, does not change (dU = n Cv dT = 0). With T constant, heat added or removed goes entirely into or out of the system as work, so Q = W and the energy balance supports T staying the same.

In an isothermal process, the relationship PV = nRT holds with T constant, so pressure and volume adjust inversely to keep their product constant (P ∝ 1/V). This contrasts with the other processes: when pressure is held constant, temperature typically changes as volume changes (T = PV/(nR) with P fixed). When volume is fixed, heat transfer changes temperature since no work is done (W = 0). In an adiabatic process, no heat is exchanged, so temperature changes as the gas expands or compresses, following relations like PV^γ = constant or TV^{γ−1} = constant.