Transfer of thermal energy: Practice Questions

Which property of metals makes them significantly better thermal conductors than non-metals?

For an object to maintain a constant, steady temperature in its surroundings, what condition must be met regarding energy transfer?

Which factor primarily affects the balance of radiation that determines the average temperature of the Earth's surface?

A metal can is filled with hot water. Which type of outer surface will radiate thermal energy the most effectively?

In terms of particles, why are metals generally much better thermal conductors than non-metals?

Explain, in terms of thermal energy transfer, why birds fluff their feathers in cold weather to reduce heat loss.

A copper rod and a glass rod of equal dimensions are heated at one end. A small piece of wax is placed at the far end of each rod.

Explain, in terms of atomic lattice vibrations and delocalised electrons, why the wax on the copper rod melts significantly faster than the wax on the glass rod.

A student conducts an experiment to investigate the different methods of thermal energy transfer.

(a) Describe the process of thermal conduction in a metal rod. In your answer, refer to the role of both atomic lattice vibrations and free (delocalised) electrons.
(b) A hot object is placed in a vacuum. State the process by which thermal energy is transferred away from the object and explain why this process is possible in a vacuum.

A solar water heater consists of a network of copper pipes inside a glass-fronted box. These pipes are connected to a water storage tank located above the collector box.

(a) The copper pipes are painted dull black. Explain why this is more effective than using shiny silver pipes for heating the water.

(b) Describe the mechanism of thermal conduction through the copper pipe wall to the water. In your answer, refer to both atomic lattice vibrations and the role of electrons.

(c) The water in the pipes is heated by the Sun. It then moves to the storage tank without the use of a pump. Using the relationship \( \rho = \frac{m}{V} \), explain how this circulation occurs in terms of density.

(d) To maintain the temperature of the water, the storage tank is insulated using a double-walled jacket with a vacuum between the walls. Explain why this vacuum is effective at reducing thermal energy loss, and state which method of thermal energy transfer is not prevented by the vacuum.