Radiation

In solar heating panels, the tubes absorb the Sun’s radiation to heat water. Why are the tubes coated black?

May/June 2015

The tubes within solar heating panels absorb the Sun’s radiation to heat water. Why is black paint used on the tubes?

May/June 2015

Which statement relating to thermal radiation is correct?

May/June 2016

A piece of bread is put beneath a red-hot electric grill so that it becomes toast. By what process does heat energy get to the bread?

May/June 2016

A student examines whether black surfaces or silver surfaces are more effective at emitting infra-red radiation. The student is supplied with two identical test tubes, one having a silver surface and the other a black surface, together with hot water.

May/June 2016

A metal box has four distinct surfaces: dull black, shiny black, dull silver and shiny silver. The box is filled with boiling water so that all four surfaces are at the same temperature. A sensor measures the amount of radiation from each surface. Which surface emits the least radiation and which surface emits the most radiation?

May/June 2017

The diagrams illustrate four identical cans, each with an outside surface that is either polished silver or coated dull black. Every can holds the same volume of water, starting at 80^{\circ}C. Following five minutes in a cool room, which can will have the water at the lowest temperature?

May/June 2018

The diagrams depict four identical cans whose outer surfaces are either polished silver or coated dull black. Each can holds the same volume of water, which starts at $80^\circ$C. After five minutes in a cool room, which can has the coolest water?

May/June 2018

Which heat transfer processes do not need a medium?

May/June 2021

By what process is heat energy transferred across the vacuum of space from the Sun to the Moon’s surface?

May/June 2022

A metal cube holds boiling water. Every vertical side of the cube is either a different colour or has a different surface texture. Matching thermometers are placed at equal distances from each vertical side. Next to which side would a thermometer show the highest temperature?

May/June 2022

A hot meal is provided in a container made from shiny metal foil. Why does the container help to keep the food hot?

May/June 2024

Which statement correctly describes a dull black surface?

May/June 2025

Four similar metal plates are placed at equal distances from a heater that gives out infra-red radiation. The plates are coated dull black, dull white, shiny black and shiny white. Which plate absorbs the greatest amount of radiation and which plate reflects the greatest amount of radiation?

Oct/Nov 2017

A heater is intended to emit thermal energy by radiation. Which design modification would reduce the thermal energy released by radiation?

Oct/Nov 2017

Several solar panels are fitted on the roof of a house. They take energy from the Sun to produce electricity and also to heat water flowing through tubes within the panels.

Oct/Nov 2018

Solar panels are used to warm water.

Oct/Nov 2019

What colour does a good absorber of infrared radiation have, and what texture does it possess?

Oct/Nov 2021

Which process of heat transfer can occur in a vacuum?

Oct/Nov 2022

Fig. 3.1 shows a man standing below an outdoor heater on a cold evening. The gas in the cylinder at the bottom of the heater is the fuel for the heater. When the heater is in use, the gas moves up to the top of the heater, where it burns.

Oct/Nov 2022

A student proposes three factors that influence the rate at which a hot object emits thermal energy by radiation. Which of these proposals are correct?

Oct/Nov 2023

Which colour does the most effective absorber of infrared radiation have, and what is its texture?

Oct/Nov 2024

Energy may be transferred by thermal radiation. Four surfaces differ in colour and texture. They are all at the same temperature and each has the same surface area. Which surface transfers energy by thermal radiation at the greatest rate?

Oct/Nov 2025

Four copper spheres have the same surface colour and the same surface texture. They differ in surface temperature and surface area. Which sphere emits infrared radiation at the highest rate?

Oct/Nov 2025

A student is studying how much thermal radiation different coloured surfaces absorb. The thermometer has a piece of white card taped to its bulb, and the bulb is positioned so that it is level with the filament of a lamp. The lamp is not on. Fig. 2.1 presents the setup with the power supply, white card, tape, clamp, stand and distance d labelled.

Oct/Nov 2025