16. The heat transfer through a solid material is primarily by:
a) Conduction
b) Convection
c) Radiation
d) Both conduction and convection
Answer: a) Conduction
17. The heat transfer through a fluid is primarily by:
a) Conduction
b) Convection
c) Radiation
d) Both conduction and convection
Answer: b) Convection
18. The Stefan-Boltzmann law relates the power radiated by a blackbody to its:
a) Temperature
b) Volume
c) Pressure
d) Density
Answer: a) Temperature
19. The coefficient of performance (COP) of a refrigerator is given by:
a) COP = Qh / W
b) COP = Qc / W
c) COP = W / (Qh – Qc)
d) COP = (Qh – Qc) / W
Answer: b) COP = Qc / W
20. The entropy change of a system can be calculated using:
a) ΔS = Q / T
b) ΔS = Q + T
c) ΔS = T / Q
d) ΔS = T – Q
Answer: a) ΔS = Q / T
