REVERSIBLE PROCESSES AND THE CARNOT CYCLE

Questions 1, 2 and 4 - 9 are multiple choice questions. In each of these questions, choose the correct answer(s) from the 4 possibilities given.

Question 1. For a quasistatic process to take place:

(a) the process must happen very quickly

(b) there must be no friction present

(c) there must be no heat transfer between the system and surroundings

(d) the system must remain in equilibrium during the process.

Question 2. For a reversible process to take place:

(a) there must be no heat transfer between the system and surroundings

(b) there must be no friction present

(c) there must be no work transfer between the system and surroundings

(d) all work and heat transfer must be quasistatic.

Question 3. Define a reversible process

Question 4. The polytropic process is theoretically:

(a) internally and externally reversible

(b) internally reversible and externally irreversible

(c) internally irreversible and externally reversible

(d) internally and externally irreversible.

Question 5. In a reversible adiabatic process:

(a) the temperature of the system and surroundings must be the same

(b) the pressure of the system is infinitesimally larger or smaller than the surroundings, during expansion or compression.

(c) there is no heat transfer across the boundary

(d) there is no work transfer across the boundary.

Question 6. For a reversible isothermal process:

(a) there is no work transfer across the system boundary

(b) the temperature of the system must always be exactly the same as the surroundings

(c) the heat transfer is equal to the work transfer

(d) there is no heat transfer across the system boundary.

Question 7. The polytropic process is externally irreversible because:

(a) the piston moves too quickly for a quasistatic heat transfer

(b) there is no temperature difference between the system and surroundings

(c) there is a finite temperature difference between the system and surroundings

(d) there is a work transfer between the system and surroundings.

Question 8. A Carnot cycle provides a measure of the maximum thermal efficiency achievable for a heat engine because:

(a) it consists of reversible processes

(b) the expansion and compression are very fast

(c) it operates between very high and low temperatures

(d) heat is received and rejected at constant temperature.

Question 9. The efficiency of the Carnot cycle is increased if:

(a) the temperature of the hot source is increased

(b) the temperature of the heat sink is increased

(c) the temperature of the heat source is increased and the heat sink decreased

(d) the temperature of the heat sink is increased and the heat source decreased.

Question 10. A Carnot cycle operates between a heat source at 340°C and a heat sink at 50°C. What is the thermal efficiency of the Carnot cycle?