Black body radiation

A group of stars is called a galaxy.

What is the name of our galaxy?

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The Sun is one of the stars in our galaxy.

What was the Sun originally formed from?

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Which of the following forces was involved in the formation of the Sun?

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Stars produce light because they release energy.

Complete the sentence.

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Visible light and infrared radiation travel from the Sun to the Earth.

Which statement describes the time taken for visible light and infrared radiation to travel from the Sun to the Earth?

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Infrared radiation has a longer wavelength than visible light.

Complete the sentence.

Choose the answer from the box.

Compared with the frequency of infrared radiation, the frequency of

The Sun and the Earth both emit infrared radiation.

How does the rate of infrared radiation emitted by the Sun compare with the rate of infrared radiation emitted by the Earth?

Give a reason for your answer.

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Figure 10 shows an old scientific model of the solar system that has now been replaced.

Which statement is a reason for replacing an old scientific model with a newer scientific model? Tick (✓) one box.

Compare the model of the solar system used now with the old model of the solar system shown in Figure 10.

Table 1 shows data about four planets.

How does the time taken for one orbit change as the mean distance from the Sun increases?

The bar chart in Figure 11 shows some of the data from Table 1.

Complete the bar chart. Use data from Table 1.

All stars have a life cycle. A, B and C in Figure 12 represent three stages in the life cycle of the Sun. The stages are in the correct order. Draw one line from each stage to the name of the stage.

Stars act like black bodies. Which statement is true for perfect black bodies? Tick (✓) one box.

Infrared waves are transverse waves.

Complete the sentence.

to the direction of energy transfer by the wave.

A student investigated how the colour of a surface affects the rate at which the surface emits infrared radiation. Figure 23 shows some of the equipment used.

The student wrote the following hypothesis: ‘The black-coloured flask will emit more infrared radiation than the silver-coloured flask during 10 minutes of cooling.’ Describe a method to test this hypothesis.

When will the flasks emit infrared radiation at the greatest rate? Give a reason for your answer. Tick (✓) one box.

Another student investigated the absorption of infrared radiation by different surface colours. The student filled four hollow metal cubes with cold water. Each cube was the same size but had a different surface colour. The cubes were then placed the same distance from an infrared heater. After 10 minutes, the student measured the temperature increase of the water inside each cube.

What was the dependent variable in this investigation?

Table 2 shows the results.

Give two conclusions that can be made from the results in Table 2.

Figure 24 shows one of the cubes. The cube is filled with water. The weight of the water exerts a pressure on the bottom of the cube.

Use the Physics Equations Sheet to answer questions 09.6 and 09.7.

Which equation correctly links area, force and pressure? Tick (✓) one box.

The water pressure at the bottom of the cube is 1500 Pa. Calculate the force of the water on the bottom of the cube.

Infrared waves are transverse waves.

Complete the sentence.

to the direction of energy transfer by the wave.

A student investigated how the colour of a surface affects the rate at which the surface emits infrared radiation. Figure 1 shows some of the equipment used.

The student wrote the following hypothesis: ‘The black-coloured flask will emit more infrared radiation than the silver-coloured flask during 10 minutes of cooling.’ Describe a method to test this hypothesis.

When will the flasks emit infrared radiation at the greatest rate? Give a reason for your answer. Tick (✓) one box.

Another student investigated the absorption of infrared radiation by different surface colours. The student filled four hollow metal cubes with cold water. Each cube was the same size but had a different surface colour. The cubes were then placed the same distance from an infrared heater. After 10 minutes, the student measured the temperature increase of the water inside each cube.

What was the dependent variable in this investigation?

Table 1 shows the results.

Give two conclusions that can be made from the results in Table 1.

Figure 2 shows one of the cubes. The cube is filled with water. The weight of the water exerts a pressure on the bottom of the cube.

Use the Physics Equations Sheet to answer questions 01.6 and 01.7.

Which equation correctly links area, force and pressure? Tick (✓) one box.

The water pressure at the bottom of the cube is 1500 Pa. Calculate the force of the water on the bottom of the cube.

There are different groups of waves in the electromagnetic spectrum.

Figure 8 shows the position of three groups of the waves.

Which letter shows the position of infrared? Tick (✓) one box.

A student investigated how the colour of a surface affects the amount of infrared the

surface absorbs. Figure 9 shows the equipment used.

Complete the sentence. Choose the answer from the box.

a control the dependent the independent

In this investigation the distance between each flask and the infrared heater

The student wrote the hypothesis: ‘Surface colour of the flask affects the amount of infrared absorbed when the heater is switched on for five minutes.’ Describe how the equipment in Figure 9 could be used to test this hypothesis.

Table 1 shows the results.

Which one of the results for the black flask is anomalous?

The anomalous result was caused by reading the thermometer incorrectly. What should the student do with the anomalous result?

Calculate the mean temperature increase for the silver flask.

Mean temperature increase = °C

What conclusion can be made from Table 1? Tick (✓) one box.

Figure 11 shows the position of three types of wave in the electromagnetic spectrum.

Which letter represents infrared in the electromagnetic spectrum?

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What is infrared used for? Tick (✓) one box.

An infrared camera produces a colour image. Different colours show different temperatures. People emit infrared radiation. Figure 12 shows how the colour of the image of a person on an infrared camera depends on the person’s body temperature.

Complete the sentence. Choose the answer from the box.

The image produced by an infrared camera of a person with a body temperature of

Rescue workers use infrared cameras to search for people trapped under rubble after an earthquake. How does the image of a trapped person change if the person’s body temperature drops from 37 °C to 33 °C?

A student investigated how the type of surface affects the amount of infrared the surface radiates. Figure 13 shows the equipment used.

Complete the sentence. Choose the answer from the box.

Describe how the equipment shown in Figure 13 would be used to compare the infrared radiation emitted from the vertical surfaces of the cube.

Table 1 shows the results.

What is the resolution of the infrared detector? Tick (✓) one box.

The bar chart in Figure 14 shows two of the results.

Complete the bar chart to show all of the results.

Give one conclusion that can be made from the results.

Figure 12 shows the electromagnetic spectrum.

Which statement is correct for the direction of the arrow in Figure 12 ? Tick (✓) one box.

Explain how the properties of X-rays make them suitable for the medical imaging of bones.

A student investigated the infrared radiation emitted from the sides of a hollow metal cube. The sides of the cube are different colours or textures. Figure 13 shows the equipment used.

Boiling water was poured into the cube. The amount of infrared radiation emitted from each vertical surface was then measured.

Boiling water is a hazard in this investigation. Suggest how the risk of harm could be reduced in this investigation.

What is the control variable in this investigation?

Table 2 shows the results.

The four temperature values in Table 2 cannot be used to show that the infrared detector gives precise readings. Give the reason why.

The student looked at the data in Table 2 and concluded: ‘A black surface always emits more infrared radiation than a white surface.’ Explain how using an infrared detector with a resolution of 1 °C would have affected the student’s conclusion.

Albedo is a measure of the amount of solar radiation reflected by an object compared to the total solar radiation incident on the object. A perfect reflector has an Albedo value of 1.0 A perfect absorber has an Albedo value of 0.0

What is the Albedo value of a perfect black body?

Figure 14 shows two points, A and B, just above the Earth’s surface.

The average Albedo value of the Earth’s surface is 0.3 The Albedo value of thick cloud varies between 0.6 and 0.9 At night the air at point A cools faster than the air at point B. Explain why.

Some objects are transparent and some objects are opaque.

Which one of the objects in Figure 5 is transparent? Tick one box.

Complete the sentence. Choose an answer from the box.

absorb reflect transmit

A student wears a white T-shirt and a red baseball cap to a party.

Why does the T-shirt look white in white light?

Explain how the colour of the baseball cap appears to change when the room lights at the party change from white to blue.

A student investigated how the type of surface affects the amount of infrared radiation the surface absorbs. Figure 6 shows the equipment that the student used.

The metal sheets absorb infrared radiation. The wax melts and the drawing pins fall off the surfaces.

In the investigation there are several variables. Draw one line from each variable to the correct description of that variable.

Variable Description

What is the main hazard in this investigation?

The drawing pin attached to the matt black metal sheet fell off first. What can be concluded from this result?

A student used a simple transformer to investigate how the number of turns on the secondary coil affects the potential difference (p.d.) across the secondary coil. The student kept the p.d. across the primary coil fixed at 2V. Figure 12 shows the results collected by the student.

Figure 12

Figure 12 contains one anomalous result. Suggest one possible reason why this anomalous result occurred.

The transformer changes from being a step-down to a step-up transformer. How can you tell from Figure 12 that this happens?

A spot-welder is a device that uses a transformer to produce a large current to join sheets of metal together. Figure 13 shows a transformer demonstrating how a large current can heat and join two nails together.

Figure 13

How does the amount of infrared radiation emitted by the nails change when the power supply is switched on?

Calculate the current from the power supply needed to provide a power output of 336 W. Use the data in Figure 13. The transformer is 100% efficient.