Black Body Radiation (AQA GCSE Physics)

Exam Questions

1 hour11 questions
1a3 marks

Higher Only

Different materials behave differently when interacting with electromagnetic radiation. Figure 1 shows three different processes occurring in which electromagnetic radiation is incident on a surface.

Figure 1

6-4-e-1a-reflect-absorb-transmit

Complete the sentences. 

Choose answers from the box. 

Each answer can be used once, more than once or not at all.

Transmission Reflection Absorption

 

     

A shows the process of ..............................

   

B shows the process of ..............................

   

C shows the process of ..............................

1b4 marks

Figure 2 lists different coloured materials and processes that occur when electromagnetic radiation is incident on these materials.

Figure 2

screenshot-2023-03-10-at-10-58-53

Draw four lines between the coloured materials and the process which they best perform.

Each colour may be used once, more than once or not at all.

1c1 mark

Describe the relationship between temperature of a body and the peak intensity of radiation it emits. 

1d1 mark

Describe the relationship between temperature of a body and the wavelength of the peak intensity of radiation it emits. 

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2a1 mark

Higher Only

Visible light radiation can be reflected, absorbed and transmitted by clear plastic. Figure 1 shows a piece of clear plastic being irradiated with visible light radiation.

Figure 1

6-4-e-2a-vl-plastic-80

State the percentage of visible light absorbed by the clear plastic.

2b1 mark

Higher Only

Complete the sentence. 

Choose an answer from the box. 

increases does not change decreases

 

     

The absorbed infra red .............................. the temperature of the glass.

2c2 marks

Higher Only

Two of the following statements are true. One of the statements is false.

Tick (✓) the boxes next to the two true statements.

   

All objects absorb infra red radiation. square
Black surfaces are poor emitters of infra red radiation. square
A hot object emits more infra red than a cooler object. square
2d1 mark

The following statement is false:

"black surfaces are good reflectors of infra red radiation".

Change one word in this statement to make it true.

Write down your new statement.

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3a1 mark

Figure 1 shows the design of a solar cooker. The cooker heats water using infrared radiation from the Sun.

Figure 1

6-4-e-3a-solar-cooker

Explain why the inside of the large curved dish is covered with shiny metal foil.

3b2 marks

State which would be the best colour to paint the outside of the metal cooking pot.

Draw a ring around the correct answer.

black silver white
  

Explain a reason for your answer.

3c1 mark

The pot reaches a constant temperature. 

Compare the processes of absorption and emission occurring in the pot. 

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1a1 mark

Explain what is meant by a perfect black body.

1b3 marks

Three identical pieces of metal are painted different colours: black, grey and silver.

The metal plates are placed an equal distance from a radiant heater, as shown in Figure 1 below.

 

Figure 1

fig-1-6-4-medium-aqa-gcse-physics

Ball bearings are then stuck onto the plates using small pieces of wax.

The heater is then turned on.

Explain what you expect to happen.

1c2 marks

Figure 2 below shows a heat sink, from the CPU of a computer.

Figure 2

fig-2-q1b-6-4-medium-aqa-gcse-physics

During normal use, the CPU gets very hot. 

The heat sink is painted black.

Explain why.

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2a1 mark

In 1800 the scientist William Hershel proposed that different colours of light have different temperatures associated with them.

To test his theory, he created a spectrum of light and placed thermometers in the different colours.

His experiment is shown in Figure 3 below.

Figure 3

fig-3-q2a-6-4-medium-aqa-gcse-physics

In addition to this he also placed another thermometer nearby, outside the spectrum of light.

Explain why he placed a thermometer outside the spectrum.

2b1 mark

In one of his experiments he placed a thermometer just to the side of the red end of the spectrum, as shown in Figure 4.

Figure 4

fig-4-q2b-6-4-medium-aqa-gcse-physics

To his surprise, he found that it gave a higher temperature reading than all of the other thermometers.

Explain why.

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3a4 marks

The graph in Figure 7 below shows the spectrum of light emitted from hot objects and how the intensity of different frequencies varies with the temperature of the object.

Figure 7

fig-7-q3a-6-4-medium-aqa-gcse-physics

The frequency range of visible light runs from around 4 cross times1014 Hz (red) to 8 cross times1014 Hz (violet). These frequencies are shown as dotted lines on the graph.

When objects are heated:

  • As they get hotter, they emit greater amounts of infra-red radiation.
  • When they get very hot, they start to glow red.
  • Heated even further they start to glow yellow.
  • Eventually an object can get so hot that it will glow white.

Use the graph in Figure 7 to explain each of the above observations.

3b2 marks

Use the graph in Figure 7 to estimate the temperature at which an object will first start to glow red. Explain your answer.

3c2 marks

Viewed high in the sky, the Sun appears white in colour.

Use the graph in Figure 7 to estimate the temperature of the Sun.

Explain your answer

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4a2 marks

Tick the correct boxes below to indicate which colour is the best absorber, and which is the best emitter, of thermal radiation.

 

Silver

Dull white

Dull Grey

Matt Black

Best absorber

       

Best emitter

       

4b3 marks

Higher Only

On a hot sunny day, it is noticed that the black leather seats in a car start to get very hot.

The temperature, however, does not continue rising forever. It eventually settles at a high but steady temperature.

Explain why, referring to the thermal radiation absorbed and emitted by the seat.

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5a2 marks

Higher Only

The diagrams in Figure 8 below show the blackbody radiation received by the Earth during daytime and at night, along with the blackbody radiation emitted by the Earth.

Figure 8

fig-8-q5-6-4-medium-aqa-gcse-physics

The width of each arrow represents the amount of radiation received or emitted.

During the day the Earth receives radiation from the Sun, but at night this radiation is no longer received.

The Earth, on the other hand, emits radiation at a fairly constant rate.

Explain, using the above information, why it is usually warmer during the daytime than it is at night.

5b3 marks

Higher Only

Clouds contain droplets of water which are very good at reflecting blackbody radiation.

Explain the effect clouds will have on the temperature during both daytime and night-time.

Make sure you refer to both the radiation received and emitted by the Earth.

5c3 marks

Higher Only

Carbon dioxide is very good at reflecting the radiation emitted from the Earth, but is transparent to the radiation received from the Sun.

Explain why increased levels of carbon dioxide could lead to a rise in the Earth’s average temperature.

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1a2 marks

Astronomers are investigating black body radiation.

Define black body radiation by using the correct words to complete the gaps in the sentence below. 

 

An object that ___________ all of the radiation incident on it and does not ___________ or transmit any radiation.

1b3 marks

The graph in Figure 1 below shows a black body radiation curve.

Figure 1

8-2-2b-q-sl-sq-easy-phy

Sketch a line on the graph for a body at 1250 °C.

1c3 marks

For one of the stars the astronomers are observing, star A, the wavelength of the highest intensity radiation is λmax = 900 × 10−9 m. 

This star has a known temperature of 3200 Kelvin.

Temperature and wavelength of highest intensity radiation are inversely proportional for a black body:

lambda subscript m a x end subscript T space equals space constant

For a second star, star B, the wavelength of the highest intensity radiation is λmax = 300 × 10−9 m. 

Modelling a star as a black body, calculate the temperature of star B.

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2a2 marks

An object which can be modelled as a black body is heated to different temperatures, represented by the four lines on Figure 1, and its spectrum is recorded on the graph. 

Figure 1

8-2-3a-q-sl-sq-easy-phy

Identify the visible, ultraviolet and infrared wavelengths by correctly labelling the sections of the graph.

2b4 marks

Using Figure 1, explain why metal turns from red to white and gets brighter as it gets hotter.

2c3 marks

Higher only

The emission and absorption of radiation plays a large role in the Earth's environment.

Use the text in the box to complete the sentences below, describing the Earth's Surface-Atmosphere system.

Carbon monoxide transfer Sun
Greenhouse gases constant space

The Earth's energy balance depends on how much energy is incoming from the _____________ and how much energy is returned to _____________.

  

If incoming and outgoing energy are in balance, the Earth’s temperature will remain ______________.

 

This system can be used to create models that help climate scientists predict temperature fluctuations based on concentrations of _________________   ____________.

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3a3 marks

Higher Only

The earth remains at a constant average temperature of ~15 °C, despite being in space which has an average temperature of -270 °C.

Explain how the Earth maintains a constant temperature.

3b4 marks

Explain why a cloudy night is warmer than a clear one.

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