Thermal Conductivity and Heat Transfer Quiz

Which of the following materials is likely to have the highest thermal conductivity?

• Wood

• Copper

• Glass

• Plastic

If the thermal conductivity of a material is 0.5 W/m·K, what is the heat transfer rate through a 2-metre thick wall with a surface area of 10 square metres and a temperature difference of 20°C across it?

• 50 W

• 100 W

• 200 W

• 500 W

Answer explanation

Using the formula Q = k * A * (ΔT / d), where k = 0.5 W/m·K, A = 10 m², ΔT = 20°C, and d = 2 m, we find Q = 0.5 * 10 * (20 / 2) = 50 W. Thus, the heat transfer rate is 50 W.

Which factor does NOT affect the rate of heat transfer by conduction?

• Thickness of the material

• Surface area

• Colour of the material

• Temperature difference

What is the unit of thermal resistance?

• W/m·K

• m²K/W

• J/kg·K

• W/m²

Which of the following is an application of thermal resistance?

• Insulation in buildings

• Electrical wiring

• Solar panels

• Wind turbines

What is the primary mode of heat transfer in a vacuum?

• Conduction

• Convection

• Radiation

• Evaporation

If a metal rod is heated at one end, which process primarily transfers heat to the other end?

• Conduction

• Convection

• Radiation

• Sublimation

Which of the following increases the thermal resistance of a wall?

• Increasing the thickness

• Decreasing the thickness

• Increasing the thermal conductivity

• Decreasing the surface area

What is the effect of increasing the surface area on the rate of heat transfer by convection?

• Decreases the rate

• Increases the rate

• No effect

• Depends on the material

Which of the following is a poor conductor of heat?

• Aluminium

• Steel

• Rubber

• Silver