Electromagnetic Waves (AQA GCSE Physics: Combined Science)

Higher Only

Radio waves are detected using metal antennae.

What happens when an antenna absorbs radio waves?

Describe how radio waves are different from gamma rays.

Higher Only

Figure 1 below shows an X-ray image of a human skull.

Figure 1

When X-rays enter the body, what does the following do to the X-rays?

(i) Soft tissue

(ii) Bone

Higher Only

X-rays are used in hospitals for computed tomography (CT) scans. 

Give two other medical uses for X-rays and state a property of X-rays that makes them useful for these.

Table 1 below shows the total dose of X-rays received by the human body when different parts are X-rayed.

Table 1

Calculate the number of chest X-rays that are equal in dose to one pelvis X-ray. 

Stars emit all types of electromagnetic waves. However, an X-ray telescope on Earth is unable to detect X-rays emitted from distant stars.

Explain why this is the case and give a solution to this problem. 

Light changes direction as it passes from one medium to another.

State the name of this phenomena and explain why this happens.

Figure 1 shows a light ray changing direction as it passes from air into a glass block.

Figure 1

Draw a light ray coming out of a glass block.

Higher Only

State the direction of the light ray in part (b) and why you have drawn it this way.

What property of the light does not change when it passes from the air to the glass block? 

Explain why this is the case.

A student carried out an experiment to test how the colour of an object affects the amount of blackbody radiation emitted by that object.

The student took two identical flasks and painted one of them black and the other silver, as shown in Figure 5 below

Figure 5

The plan was to fill them both with hot water and then measure how their temperatures changed over time.

Suggest two other things that the student should have done in order to ensure a fair test.

The graph in Figure 6 below shows the students results for the silver flask.

Figure 6

Add another line to the graph in Figure 6 showing the results you'd expect the student to get for the black beaker.

After leaving the silver flask for a long period of time, the temperature of the beaker finally settled at 20 degrees Celsius.

Explain what is significant about this temperature.

How would the final temperature of the black flask compare to the temperature of the silver flask?

Figure 1 shows the apparatus that a student used to investigate the heating effect of different wavelengths of light.

Figure 1

The student put thermometer D outside of the light spectrum.

Suggest why.

Table 1 gives the position and reading of each thermometer 10 minutes after the investigation started.

Table 1

Summarise the results of Table 1, referring to wavelength in your answer.

A similar investigation completed in 1800 by the scientist Sir William Herschel led to the discovery of infrared radiation.

Suggest how the student could show that the spectrum produced by the glass prism has an infrared region.

A thermal imaging camera detects infrared radiation. Electronic circuits inside the camera produce a visible image of the object emitting the infrared radiation.

At night, police officers use thermal imaging cameras to track criminals running away from crime scenes.

Thermal imaging cameras work better at night than during the day.

Explain why.

When metal is exposed to infrared radiation, its temperature increases and it emits visible light.

In terms of photons and energy levels of the metal atoms, explain why visible light is emitted. 

As the metal receives higher energy infrared radiation, it becomes hotter and the visible light emitted changes from red to yellow.

Suggest why the colour changes.

Higher energy electromagnetic radiation is dangerous and is often described as "ionising radiation".

Explain why it has this name.

The scientific unit of measurement used to measure the dose received from radiation, such as X-rays or background radiation, is the millisievert (mSv).

Table 1 shows the X-ray dose resulting from CT scans of various parts of the body.

Table 1 also shows the time it would take to get the same dose from background radiation.

Table 1

A student suggests that the X-ray dose and the time it would take to get the same dose from background radiation are directly proportional.

Use calculations to test this suggestion and state your conclusion.

Table 1 shows information about the electromagnetic spectrum.

Table 1

Show that the speed of electromagnetic radiation is 3 × 10⁸ m/s, then calculate the wavelength of these ultra-violet waves in nm.

Give your answer to 2 significant figures.

Wavelength (2 significant figures) = .................................... nm

Ultra-violet waves can damage human skin.

Describe the damage caused to human skin by ultra-violet waves.

Sun cream can be used to protect skin from ultra-violet waves. Sun creams have different sun protection factors (SPF).

Figure 1 shows the information written on the back of a bottle of sun cream.

Figure 1

A doctor says ‘adults should not sunbathe for more than 20 minutes in the midday sunshine when not using sun cream’.

If an adult used sun cream with SPF 6, calculate how long they could safely sunbathe for.

Ultrasound and X-rays are used to scan patients in hospital.Table 1 contains information about these two different waves.

Table 1

Ultrasound and X-rays are used to scan different parts of the patient.

Explain how ultrasound and X-rays are used and evaluate the risks and benefits of using these two different waves to scan patients in hospital.

Use the information in the table in your answer.