# Heat Transfer Questions and Answers – Thermal Conductivity of Different Materials

This set of tough Heat Transfer Questions focuses on “Thermal Conductivity Of Different Materials”.

1. What is the thermal conductivity of asphalt in W/m K?
a) 0.064
b) 0.063
c) 0.062
d) 0.061

Explanation: Asphalt concrete has three main structural elements i.e. aggregates, binder and the contact layer between them. It is soft at high temperatures but brittle at low temperatures.

2. Which one is having the highest thermal conductivity?
a) Silver
b) Copper
c) Glass
d) Earth

Explanation: Thermal conductivity of silver is 410 W/m degree while that of copper, glass and earth are 385 W/m degree, 0.75 W/m degree and 0.138 respectively.

3. What is the thermal conductivity of magnetite in W/m K?
a) 3.7
b) 3.8
c) 3.9
d) 4.0

Explanation: This is having low thermal conductivity because of high intramolecular interactions between their outer edge molecules.

4. Which one is having the lowest thermal conductivity?
a) Furnace
b) Wool
c) Saw dust
d) Glass wool

Explanation: Thermal conductivity of glass wool is 0.03 W/m degree while that of a furnace, wool and saw dust are 0.30 W/m degree, 0.052 W/m degree and 0.07 respectively.

5. What is the thermal conductivity of coal in W/m K?
a) 0.25
b) 0.26
c) 0.27
d) 0.28

Explanation: Coal is composed primarily of carbon along with variable quantities of other elements such as hydrogen, sulfur, oxygen and nitrogen.
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6. What is the thermal conductivity of cotton in W/m K?
a) 0.03
b) 0.04
c) 0.05
d) 0.06

Explanation: It is a soft material that grows in a protective capsule, around the seeds of cotton plants.

7. Which one is having the highest thermal conductivity?
a) Brass
b) Aluminum
c) Cast iron
d) Steel

Explanation: Thermal conductivity of aluminum is 225 W/m degree while that of brass, cast iron and steel are 107 W/m degree, 55 W/m degree and 20 respectively.

8. What is the thermal conductivity of apple in W/m K?
a) 0.513
b) 0.613
c) 0.713
d) 0.813

Explanation: It is a sweet fruit that has very low thermal conductivity in order to prevent it from damage.

9. What is the thermal conductivity of ice in W/m K?
a) 1.55
b) 1.66
c) 1.77
d) 1.88

Explanation: Frozen water in the form of an ordinary household ice cube. The white zone in the center is the result of tiny air bubbles.

10. Which one is having the lowest thermal conductivity?
a) Ash
b) Ice
c) Freon
d) Water

Explanation: Thermal conductivity of freon is 0.0083 W/m degree while that of ash, ice and water are 0.12 W/m degree, 2.25 W/m degree and 0.55 respectively.

Sanfoundry Global Education & Learning Series – Heat Transfer.

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