Uses and hazards of electromagnetic waves

Some homes are connected to the internet using satellites.

Electromagnetic waves are used to transmit data between Earth and the satellites.

Which electromagnetic waves are used to transfer data between Earth and satellites?

Tick () one box.

Which of the following electromagnetic waves has the greatest frequency?

Tick () one box.

What is meant by the ‘period of a wave’?

Tick () one box.

Data is transmitted to the satellites by electromagnetic waves with a frequency of 48 GHz.

Calculate the period of waves with a frequency of 48 GHz.

Use the Physics Equations Sheet.

Choose the unit from the box.

The satellites receive and transmit data using electromagnetic waves with different frequencies.

Give one property that is the same for electromagnetic waves with different frequencies.

Most homes are connected to the internet using cables.

Suggest one reason why homes in some areas of the UK are connected to the internet by satellites.

Electromagnetic waves are grouped according to their wavelength and frequency.

Electromagnetic waves are transverse waves and can travel through a vacuum.

Give one other property that is the same for all types of electromagnetic wave.

What is meant by ‘transverse wave’?

Which group of electromagnetic waves is used for satellite communications?

Visible light is the only group of electromagnetic waves that the human eye can detect.

Which colour of visible light has the shortest wavelength?

The three highest frequency groups of electromagnetic waves are hazardous.

Describe a risk linked to each group of high frequency electromagnetic wave.

Figure 5 shows a person using a mobile phone to allow a laptop to access

the Internet.

The electromagnetic waves emitted by the mobile phone send information to the laptop.

The electromagnetic waves emitted by the mobile phone have a period

Calculate the frequency of the waves.

Use the Physics Equations Sheet.

Give your answer in standard form.

The electromagnetic waves are produced by oscillations in the transmitter of the mobile phone.

Explain how oscillations in the transmitter enable information to be transferred to the detector in the laptop.

There are different types of electromagnetic waves.

What do all electromagnetic waves transfer? Tick (✓) one box.

Complete the sentence. Choose answers from the box.

Different types of electromagnetic waves have a different

Figure 1 shows the electromagnetic spectrum.

Give the names of parts A and B of the electromagnetic spectrum.

Different types of electromagnetic waves have different uses. Draw one line from each type of electromagnetic wave to its use. Type of electromagnetic Use wave

A student investigated how the colour of a surface affects the power of the infrared radiation emitted by the surface. Figure 2 shows the equipment used.

The infrared detector measures the power of the infrared radiation emitted by

the flasks.

The student poured hot water into each flask. What should the student do to reduce the risk of burning herself with the hot water?

Describe how the student should use the equipment in Figure 2 to compare the power of the infrared radiation emitted by each surface.

A student investigated how the power of the infrared radiation emitted from a flask

changed with time. Table 1 shows the results.

Describe the pattern shown by the data in Table 1.

What is the most likely value for the power of the infrared radiation emitted after 480 seconds? Use Table 1. Tick (✓) one box.

A Leslie Cube is used to demonstrate that different surfaces emit different amounts of

infrared radiation. Figure 3 shows an infrared detector and a Leslie Cube filled with hot water.

Give one advantage of using a Leslie Cube rather than the equipment in Figure 2 on page 4.

The teacher improved the demonstration by using four infrared detectors connected to a data logger and computer. Each detector was pointed at a different surface of the Leslie Cube. The distance between the surface and the detector was the same in each case. Give two reasons why this improved the demonstration.

Different parts of the electromagnetic spectrum are used in medical imaging. Figure 8 shows an image of a person’s hand taken with an infrared camera.

Explain why the infrared camera is able to show that parts of the hand are at different temperatures.

Infrared has a range of wavelengths from 700 nm to 1 mm. Which part of the electromagnetic spectrum would have waves with a wavelength of

Tick (✓) one box.

Figure 9 shows X-rays and gamma rays being used for medical imaging.

Figure 9

To use X-rays for medical imaging, a machine produces a very brief burst of X-rays. To use gamma rays for medical imaging, a radioactive isotope is injected into the patient’s blood. The isotope is circulated around the body in the blood. The isotope emits gamma rays.

Compare the potential risks to a patient of using X-rays and gamma rays for medical imaging.

X-rays are produced by colliding high-energy electrons into a metal target. The electrons have high energy because they are accelerated to high speeds. Only a small proportion of the kinetic energy of an electron is converted into an X-ray when it collides with the metal target.

An electron is accelerated through a distance of 15 mm. The work done on the electron is 1.2 × 10^–13 J. Calculate the force on the electron.

The metal target is made from tungsten. Tungsten has the highest melting point of any metal. Explain why using tungsten as the metal target enables the X-ray machine to be more powerful.

X-rays and gamma rays are types of electromagnetic waves. X-rays are used for medical imaging.

Which substance will not absorb X-rays? Tick (✓) one box.

Table 1 shows the effect of exposure to different doses of radiation.

During one X-ray a person receives a dose of 0.100 mSv Why is this dose unlikely to harm the person?

A doctor takes an X-ray photograph of a person. When taking the X-ray photograph, the doctor stands behind a screen. Suggest why.

Which of the following are gamma rays used for? Tick (✓) one box.

Why are gamma rays and X-rays harmful to humans? Tick (✓) one box.

Electromagnetic waves are also used in communications. Describe how microwaves and visible light are used in communications.

The Sun emits all types of electromagnetic waves.

Figure 7 shows the electromagnetic spectrum.

Complete the sentences.

Choose answers from the box.

Explain why it is important that the Earth’s atmosphere absorbs gamma rays emitted by the Sun.

Some microwaves are not absorbed by the Earth’s atmosphere.

Why is this useful?

Some ultraviolet (UV) radiation from the Sun passes through the atmosphere and reaches the surface of the Earth.

The amount of UV radiation that reaches the surface of the Earth can be measured on a scale called the UV index.

Figure 8 shows the average midday UV index in the UK for 1 year.

Why is exposure to UV radiation harmful to humans?

Compare the risk from UV radiation at different times of year in the UK.

Use data from Figure 8.

Figure 5 shows types of waves within the electromagnetic spectrum.

Some of the types of waves are represented by letters.

Which letter shows the position of ultraviolet (UV) radiation within the electromagnetic spectrum?

Tick one box.

A special lamp can produce UV radiation.

Which two statements describe the electromagnetic waves emitted by a UV lamp?

Tick two boxes.

UV radiation is used to treat a vitamin D deficiency.

People should not use a UV lamp for long periods of time.

State two risks of exposure to high levels of UV radiation.

Ionising radiation is used for some medical imaging.

Name two types of electromagnetic waves that are used.