Electromagnetic waves

Draw one straight line from each electromagnetic radiation to its correct description.

Different colours of light have different frequencies.

Which of these colours has the highest frequency?

Figure 2 is a diagram of a glass block being used to investigate the refraction of light.

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Figure 2

The angle of incidence was varied and the angle of refraction was measured each time.

Figure 3 shows the results in a table.

Figure 4 shows a graph of these results.

The two shaded rows in Figure 3 are not plotted on the graph in Figure 4.

Plot these missing results on the graph in Figure 4.

Draw a curve of best fit through the points on the graph in Figure 4.

Using Figure 4, describe the relationship between the angle of refraction and the angle of incidence.

When light travels from air into glass, it is refracted.

To investigate this, a student has a rectangular glass block and a ray box.

The ray box produces a ray of light.

Describe how the student should use the glass block and ray box to produce a refracted ray and mark its position.

You may draw a diagram to help your answer.

Figure 9 is a table of data for three coloured beams of light travelling from air into glass.

Using data from Figure 9,

state what happens to the wavelength of light when the light travels from glass into air

state what happens to the frequency of light when the light travels from glass into air.

The speed of blue light in air is 3.0 × 10⁸m / s.

Calculate the change in the speed of blue light when it travels from air into glass.

Use the equation

v = f × λ

change in speed =_........

This question is about the electromagnetic spectrum.

X-rays and microwaves are both parts of the electromagnetic spectrum.

Use words from the box to complete the sentences.

amplitude frequency longitudinal speed transverse wavelength

X-rays and microwaves are both_........ waves.

In a vacuum, x-rays and microwaves always have the same_........ .

X-rays always have a higher_........ than microwaves.

Figure 1 shows the full electromagnetic spectrum.

Figure 2 gives information about four of the types of electromagnetic radiation shown in Figure 1.

State the name of each type of radiation next to its information.

Ultraviolet (UV) waves from the Sun travel towards the Earth.

Ultraviolet waves can be grouped by wavelength.

The three groups of wavelengths are UVA, UVB and UVC.

Figure 7 shows, for each group,

• the wavelength range

• the effect of the Earth’s atmosphere on each type of UV wave.

Explain why UVC is potentially the most dangerous ultraviolet radiation but does not cause harm to people.

The speed of electromagnetic radiation is 3 00. 10⁸ m/s.

Calculate the frequency of the shortest wavelength of UVB radiation.

UV radiation of wavelength 365 nm is used to detect forged banknotes.

In a genuine banknote there are marks that cannot be seen using visible light. These marks can be seen using UV radiation.

Explain why the marks can be seen when the UV radiation shines on the banknote.

Your answer should refer to the energy of electrons in atoms.

You may draw a diagram to help with your answer.

This question is about waves in the electromagnetic (e-m) spectrum.

Figure 1 shows some types of radiation that form part of the e-m spectrum and some uses of e-m radiation.

Draw one straight line from each type of e-m radiation to its use.

One line has been drawn for you.

Which of these waves has the highest frequency?

X-rays are also part of the e-m spectrum.

Figure 2 shows an airport security scanner using X-rays to scan passengers’ bags.

Explain why X-rays are used to scan passengers’ bags.

Explain why passengers are not scanned with X-rays.

Figure 9 shows two technicians, L and M, measuring the speed of sound in air.

L fires a starting pistol.

M starts a stopwatch when first seeing the smoke from the starting pistol.

M stops the stopwatch when hearing the bang made by the starting pistol.

The distance between L and M is 120 m.

M’s reaction time is 0.23 s.

The speed of sound in air is 330 m / s.

Calculate M’s reaction time as a percentage of the time sound takes to travel from L to M.

Which of these would improve the technicians’ measurement of the speed of sound?

Figure 10 shows the difference in refraction of sound waves and light waves when these waves travel from air into water.

Explain why the refraction of the sound wave is different from the refraction of the light wave in Figure 10.

Light is one example of an electromagnetic wave.

Light can transfer energy from a lamp to the leaf of a plant, causing chemical reactions in the leaf.

Describe examples of two other electromagnetic waves transferring energy.

Figure 1 shows how the visible spectrum of white light is shown on a screen.

Which of these is the best piece of equipment to produce the white light?

Which colour is seen between yellow and blue in the spectrum on the screen?

Figure 2 shows the main parts of the electromagnetic spectrum.

Complete the following sentences using information from Figure 2. Each part of the electromagnetic spectrum may be used once, more than once or not at all.

The part of the electromagnetic spectrum used to detect broken bones is

The part of the electromagnetic spectrum used in thermal imaging is

The part of the electromagnetic spectrum that

• is used to cook food

AND

• has a shorter wavelength than microwaves is

The part of the electromagnetic spectrum that

• is used to sterilise medical equipment

AND

• has a shorter wavelength than x‑rays is

This question is about waves in the electromagnetic (e.m.) spectrum.

The potential danger associated with the waves of the e.m. spectrum increases as

A microwave oven uses waves of frequency 2.45 GHz.

Calculate the wavelength of the microwaves.

The microwave oven is 55% efficient and transfers 42 000 J of energy to some food when it is heated.

Calculate the total amount of energy that must be supplied to the oven.

*(c) X-rays and radio waves are part of the electromagnetic spectrum and have different uses.

These radiations are produced in different ways.

X-rays are emitted when electrons within an atom go through energy changes.

Radiowaves are produced by electrons in circuits.

Compare X-rays with radio waves.

Your answer should refer to

• the uses of both types of radiation

• the different ways that electrons are involved in producing X-rays and radio waves.

Figure 1 shows the parts of the electromagnetic spectrum.

Which row of the table names the parts J, K and L of the electromagnetic spectrum?

All electromagnetic waves can travel in a vacuum.

Which of these is the same for all electromagnetic waves travelling in a vacuum?

X-rays can be useful and harmful to humans.

State one way that x-rays are useful to humans.

State one way that x-rays are harmful to humans.

A person warms their hands in front of a hot fire as shown in Figure 2.

Use words from the box to complete the following sentences.

chemical infrared radio thermal ultraviolet

The electromagnetic waves that the fire mostly emits are_........ waves.

These waves transfer_........ energy to the hands.

A student is investigating the refraction of light.

Figure 5 shows part of the apparatus and the angles to be measured.

The student measures angle r for several different values of angle i.

Figure 6 shows the student’s results.

On the graph in Figure 6, draw the best fit curve.

Use the graph in Figure 6 to estimate the value of angle r when angle i is 80°.

Describe how angle r changes with angle i for the results shown on the graph in Figure 6.

In Figure 5, the frequency of the light remains the same in glass as in air.

Which row of the table describes what happens to the wave velocity and to the wavelength of the light when the light travels from air to glass?

In Figure 7, only refraction of light is shown.

Other things happen to the light as it travels from P to Q.

The intensity (brightness) of the light at Q is less than the intensity of the light at P.

Explain the decrease in intensity as the light travels from P to Q.

You may add to Figure 7 to help your answer.

Draw one line from each use of wave to the matching electromagnetic wave.

One line has been drawn for you.

Ultraviolet light has a higher frequency than infrared light.

Which of these colours of visible light has the highest frequency?

Figure 1 shows how the brightness of a source of light changes with wavelength.

Describe how the brightness changes with wavelength.

Which of these describes isotopes of an element?

Figure 9 represents a decay that can happen inside the nucleus of an atom.

Which decay is represented in Figure 9?

The half-life of cobalt-60 is 5 years.

A school cobalt source had an activity of 38.5 kBq in the year 2000.

Estimate the activity of this source in the year 2020.

Explain what can happen to the body if a person has a prolonged exposure to gamma rays.

A G-M tube is connected to a counter. A teacher places the G-M tube near to a radioactive source. A student starts the counter and clock at the same time and writes down the readings shown on the counter every 15 s.

The student plots the readings with a line of best fit, as shown in Figure 10.

Calculate the average count rate, in counts / s, from the graph.

Show your working on the graph.

average count rate =_........ counts / s

The student says that the experiment must have been done carelessly because the data seemed quite scattered away from the best fit line.

The teacher claims such results should be expected in radioactivity experiments.

Justify the teacher’s claim.

Which colour of visible light has the longest wavelength?

Some television remote controls use infrared radiation and other remote controls use radio waves.

Explain why an infrared remote control may not switch on the television from behind an armchair but a radio wave remote control always will.

Figure 2 is a diagram of a water wave.

A cork is floating on the water.

Use the scale on the diagram to measure the wavelength of the wave.

Describe the motion of the cork.

You should include how the cork moves relative to the direction of travel of the wave.

A different water wave has a wavelength of 0.25 m and a frequency of 1.5 Hz.

Calculate the wave speed.

Some sunglasses have photochromic lenses.

Photochromic lenses are clear when the lenses are indoors but they darken in bright sunlight to reduce the effects of the sunlight.

Photochromic lenses react to ultraviolet light.

Suggest a benefit of making the lenses go dark with ultraviolet light.

Radio waves from Jupiter take 40 minutes to reach Earth.

Light waves from the Sun take 8 minutes to reach Earth.

Calculate how many times further it is from Earth to Jupiter than from Earth to the Sun.

State the property of electromagnetic radiation that is used in your answer.

Ultraviolet waves cover a range of frequencies.

Scientists divide this range into three types, UVA, UVB and UVC.

The table in Figure 14 shows the frequency range for each type.

Figure 15 is a diagram about the effect that the Earth’s atmosphere has on three types of ultraviolet radiation.

Describe how the effects change with wavelength, using information from Figure 14 and Figure 15.

The width of the arrows drawn indicates the amount of radiation that is involved.

Calculations are not required.

*(d) Radio waves and gamma radiation are at opposite ends of the electromagnetic spectrum.

Compare how these two electromagnetic radiations are produced.

A student investigates what happens when light travels from air to glass.

Figure 15 shows some of the apparatus used in the investigation.

In Figure 15, angle Y is the angle of

Figure 16 is a graph of the student’s results.

Use the graph to calculate a value for

The student concludes that angle Y is directly proportional to angle X.

Explain what the student must do to test this conclusion in more detail.

The speed of light is 3.0 × 10⁸m/s.

The wavelength of yellow light is 5.8 × 10⁻⁷m.

Calculate the frequency of yellow light.

State the unit.

Use the equation

Give one colour of light that has a longer wavelength than yellow light.

Give one colour of light that has a higher frequency than yellow light.

Figure 7 shows a tuning fork.

When the prongs of the tuning fork are struck, the prongs vibrate in the directions shown by the arrows on Figure 7.

Describe how the vibrating tuning fork causes a sound wave to travel through the air.

You may add to the diagram if it helps your answer.

The following descriptions describe waves from different parts of the electromagnetic spectrum.

Complete each description by adding the name of the wave.

Use the name of each wave only once. Each description refers to a different part of the electromagnetic spectrum.

Description 1

used in cooking

used in short-range communication

typical wavelength 900 nm

Description 2

used in cooking

used in communication

typical wavelength 150 mm

Description 3

used in communication

produced by oscillations in electrical circuits

typical wavelength 150 m

Description 4

used in medical scanning

is emitted by the nucleus of an atom

typical wavelength 2.0 × 10⁻³ nm

When white light crosses the boundary between air and glass, it can split up into the colours of the spectrum.

Explain, in terms of speed, why the light behaves like this.