For a system undergoing isothermal process, heat energy is supplied to the system. Choose the option showing correct statements (a) Internal energy will increase (b) Internal energy will decrease (c) Work done by system is positive (d) Work done by system is negative (e) Internal energy remains constant
In an isothermal process, the temperature of the system remains constant. According to the first law of thermodynamics, the change in internal energy (\Delta U) of a system is given by:
\Delta U = Q - W
Where:
Q is the heat added to the system.
W is the work done by the system.
For an isothermal process applied to an ideal gas, the internal energy, which is a function of temperature, remains constant. Thus, \Delta U = 0, meaning:
The internal energy does not change. Hence, option (e) is correct: Internal energy remains constant.
Since \Delta U = 0, we have:
Q = W
This implies that the work done by the system is equal to the heat supplied to the system. Given that heat energy is supplied, the system does positive work. Therefore, option (c) is correct: Work done by the system is positive.
Let's evaluate the options:
(a) Internal energy will increase: Incorrect. The internal energy remains constant as the process is isothermal.
(b) Internal energy will decrease: Incorrect. The internal energy remains constant.
(c) Work done by the system is positive: Correct. Heat supplied to the system results in positive work done.
(d) Work done by the system is negative: Incorrect. The work done is positive due to heat added.
(e) Internal energy remains constant: Correct. As temperature remains constant, internal energy does not change.
