1. Generally the external thermal resistance between the surface of the body and the environment is

a. less than the internal conduction resistance in the body
b. more than the internal conduction resistance in the body
c. same as the internal conduction resistance in the body
d. none of the above

ANSWER: b. more than the internal conduction resistance in the body

2. Suppose that a hot metal ball is immersed in cold water, then temperature distribution in the body depends upon

a. thermal conductivity of the body
b. convective heat transfer from the body surface to water
c. both a. and b.
d. none of the above

ANSWER: c. both a. and b.

3. Suppose that a hot metal ball is suddenly immersed in cold water. What is the condition for the ball to maintain it at a uniform temperature?

a. the conduction resistance in a ball should be very large compared to the convection resistance for heat transfer from surface of ball to water
b. the conduction resistance in a ball should be very small compared to the convection resistance for heat transfer from surface of ball to water
c. the conduction resistance in a ball should be equal to the convection resistance for heat transfer from surface of ball to water
d. cannot say

ANSWER: b. the conduction resistance in a ball should be very small compared to the convection resistance for heat transfer from surface of ball to water

4. What is lumped heat capacity analysis?

a. the analysis of a system in which it is assumed to be at nonuniform temperature
b. the analysis of a system in which it is assumed to be at uniform temperature
c. the analysis of a system in which it is assumed to be at either uniform or nonuniform temperature
d. none of the above

ANSWER: b. the analysis of a system in which it is assumed to be at uniform temperature

5. The Biot number or Biot modulus is given by

a. the ratio of external convection resistance to the internal conduction resistance
b. the ratio of internal conduction resistance to the external convection resistance
c. multiplying internal conduction resistance and external convection resistance
d. none of the above

ANSWER: b. the ratio of internal conduction resistance to the external convection resistance

6. What is the correct formula for The Biot number?

a. hl/k
b. k/hl
c. l/hk
d. hk/l

7. What should be the Biot number to assume the body at uniform temperature?

a. the Biot number should be less than 0.1
b. the Biot number should be more than 0.1
c. the Biot number should be equal to 0.1
d. none of the above

ANSWER: a. the Biot number should be less than 0.1

8. The cooling of a metal ball of volume V, in large quantity of fluid is analogous to

a. discharging of battery in an electric system
b. discharging of capacitor in an electric system
c. generation of heat in resistor in an electrical system
d. none of the above