Transfer of Thermal Energy (CIE IGCSE Physics: Co-ordinated Sciences (Double Award))

Some materials are poor conductors of thermal energy (heat energy).

State the term that describes materials that are poor conductors of thermal energy.

Some materials are good conductors of thermal energy.

Draw a ring around each material that is a good conductor of thermal energy.

A student has two rods made of different materials. The rods are the same size.

Describe an experiment to identify which material is the better conductor of thermal energy.

You may draw a diagram in the space below.

Extended Tier Only

Fig. 4.1 shows a cold plastic spoon that has just been placed in hot liquid in a cup.

Describe, in terms of molecules, why the temperature of the whole of the spoon increases.

Extended Tier Only

The plastic spoon is replaced by a metal spoon.

 
Describe an additional process by which the temperature of the whole of this spoon increases.

A student constructs a device for absorbing thermal energy from the Sun. Fig. 6.1 shows the device.

The student places the white plastic pipe in sunlight. The cold water flows slowly from Tank A to Tank B. Energy from the Sun heats the water in the pipe.

Fig. 6.2 shows the temperatures in Tank A and Tank B.

Determine the rise in temperature of the water.

temperature rise = .................................................... °C 

The student wants to increase the thermal energy absorbed by the water in the pipe. Suggest three improvements he can make to increase the thermal energy absorbed.

Describe how the thermal energy is transferred from the Sun to the water inside the pipe.

A student investigates the thermal energy lost from two metal cans, X and Y. The cans are identical apart from their outside colour.

The student pours the same volume of hot water into each can and seals each can. The student records the temperature of the water in each can at regular time intervals for a period of 35 minutes.

The equipment is shown in Fig. 6.1.

Fig. 6.2 is a graph of the results from the investigation.

For can X, use Fig. 6.2 to determine the drop in temperature of the water

Explain why the water cools at a greater rate during the first five minutes of the experiment, compared with the last five minutes.

The outside of one can is dull black and the outside of the other is shiny white.

State the colour of can Y. 

Explain your answer.

A student heats some water in a metal can, as shown in Fig. 6.2.

Complete the sentence. Choose a word from the box.

Thermal (heat) energy moves through the metal can by ............................................

Extended Tier Only

Describe how thermal energy is transferred throughout the water. Include your ideas about density changes.

Extended Tier Only

A thermometer is used to measure the temperature inside a room in a house.

State a physical property that varies with temperature and can be used in a thermometer.

Fig.6.1 shows how the temperature of the room changes between 6:00 pm and 11:00 pm.

A heater in the room is switched on at 6 pm. The room has a large window. A large amount of thermal energy is transferred through the window. The window in the room has thick curtains.

                                  
Closing the curtains reduces the loss of thermal energy from the room.

In cool climates, people use mineral wool to reduce heat loss from houses. Mineral wool is made of fibres and trapped air, as shown in Fig.6.2.

Use words from the box to complete the sentences. Each word may be used once, more than once, or not at all.

 

Air is a good ............................................ .

 
When air is trapped between fibres, it reduces heat loss by ..................................... and by ........................................ .

Extended Tier Only

A student wants to investigate good and bad absorbers of thermal radiation. She has the apparatus shown in Fig. 5.1, a supply of cold water and a metre rule.

Explain how the student could use the apparatus she has available to carry out her investigation.

Describe the results she would expect to obtain. Draw a diagram of the set-up.

Extended Tier Only

The apparatus shown in Fig. 1.1 is known as Leslie’s Differential Air Thermometer.

The heater is switched off. Tap T is opened so that the air on the two sides of T has the same pressure. Tap T is then closed.

A gym has a low initial temperature. A larger radiant heater is placed on the floor in the centre of a gym to heat the room. The room has no open windows or ventilation. 

Describe and explain the subsequent motion of air in the gym, naming any processes. 

After a marathon in winter, the athlete has sweated a large amount. 

For the end of the marathon, the athlete's coach has a double-walled vacuum flask (Fig. 1.2), which is designed to maintain the temperature of its contents. It is partially filled with a hot liquid.

The lid is made of black plastic and sealed tight. The walls are silvered metal.

Eventually the liquid cools. Explain how thermal energy is transferred from the hot liquid through the lid over time.

A student is testing how different surfaces absorb radiant heat.

The student puts two metal plates in holders and places them on either side of a radiant heater as shown in Fig. 6.2. One plate has a shiny metal side facing towards the heater and the other plate has a dull black side facing towards the heater.

A metal disc is attached to each plate using wax.