CAIE IGCSE Physics 2.3.3 Radiation Topic Practice

Fig. 5.1 shows an aluminium block after leaving a furnace in a factory.

Fig. 5.1 shows a factory worker standing 3 m from the block.

State and explain the main process by which thermal energy is transferred to the worker.

Fig. 6.1 shows a road next to the sea.

In countries where it is usually hot, houses are often painted white.
What is the reason for this?

Fig. 6.1 shows a road next to the sea.

On a sunny day, the Sun warms the road.

Describe how energy from the Sun reaches the Earth and warms the road.

In some countries, the soil is too cold for plants to grow well. In these countries, plants are grown in plastic pots and kept inside. The pots, containing soil, are placed on sand. The sand is heated using an electrical heater, as shown in Fig. 4.1.

The heating element in Fig. 4.1 remains switched on. The temperature of the sand remains constant at a value above room temperature.

Explain why the temperature of the sand remains constant.
[Total: 11]

A silver spoon has a thermal capacity of $7.2 \mathrm{~J} /{ }^{\circ} \mathrm{C}$.

The spoon is removed from the boiling water and immediately it begins to transfer energy to the surroundings. The temperature of the surroundings is $22^{\circ} \mathrm{C}$.

On Fig. 5.1, sketch a graph to show how the temperature of the spoon changes with time from the instant that it is removed from the water.

[Total: 8]

The Earth's surface absorbs incoming radiation from the Sun and also emits thermal radiation from its surface.

Over the past 50 years, scientists estimate that the average temperature of the Earth's surface has increased by approximately $0.75^{\circ} \mathrm{C}$.

Explain what is causing this average temperature rise.

Fig. 5.1 shows a heater in a bathroom.

The heater is at a very high temperature and it glows red. The manufacturer states:
"The heater emits light and radiation and it transfers thermal energy by radiation."

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.

A metal container is used to cook food. The metal container has thick walls. Hot cooking oil at a temperature of $120^{\circ} \mathrm{C}$ is poured into the container.

The metal container is spherical. The spherical container has a smaller surface area than a long, thin container of the same volume.

Explain the advantage of using a spherical container.