Electromagnetic waves

Radio waves are one type of electromagnetic wave.

What are two properties of all electromagnetic waves?

Tick () two boxes.

A thin sheet of metal stops all electromagnetic waves.

All electromagnetic waves are longitudinal.

All electromagnetic waves have the same speed in a vacuum.

All electromagnetic waves transfer energy.

Water reflects all electromagnetic waves.

A teacher used a radio transmitter, a metal sheet and a radio receiver to demonstrate the reflection of radio waves.

Figure 9 shows the path of the radio waves from the transmitter to the metal sheet.

The teacher placed the radio receiver at positions A, B, C and D.

Which position was the radio receiver at when the radio waves were detected?

Tick () one box.

A B C D

The frequency of the radio wave was 2400 MHz.

The speed of the radio wave was 3.0 × 10⁸ m/s.

Calculate the wavelength of the radio wave.

Use the Physics Equations Sheet.

The aerial of the receiver absorbs radio waves.

Explain why the frequency of the alternating current in the receiver circuit depends on the frequency of the radio waves.

The electromagnetic spectrum is grouped into different types of wave.

Draw one line from each type of wave to a use of the wave.

Infrared radiation is emitted by heaters.

A student investigated the absorption of infrared radiation by a black surface and by a white surface.

Figure 2 shows some of the equipment used.

This is the method used.

1. Ensure that the initial temperature shown on the thermometers is the same.

2. Switch on the infrared heater.

3. Record the temperature shown on each thermometer every 30 seconds for 5 minutes.

What equipment should the student have used to measure time?

The distance between the infrared heater and each thermometer was kept the same throughout the investigation.

What type of variable was the distance?

Tick (✓) one box.

A control variable

A dependent variable

An independent variable

What was a risk to the student in the investigation?

Tick (✓) one box.

Burns from the infrared heater

Misreading the thermometers

Wearing safety glasses

Figure 3 shows the results.

What was the temperature of the room where the investigation took place?

Use Figure 3.

Temperature = ______________ ° C

What two conclusions can be made from Figure 3?

Tick (✓) two boxes.

The black surface absorbed all the infrared radiation.

The black surface had a greater temperature increase per second.

The black surface reflected all the infrared radiation.

The black surface was a better absorber of infrared radiation.

The black surface was a better reflector of infrared radiation.

Figure 4 shows a thermometer with a grey surface.

The investigation was repeated using this thermometer.

The distance between the thermometer and the heater was the same as in the first investigation.

The room temperature was the same as the first investigation.

Draw a line on Figure 3 to predict the results for the thermometer shown in Figure 4

The electromagnetic spectrum is grouped into different types of wave.

Each type of wave has different uses.

Complete the table.

A student investigated the absorption of infrared radiation by a black surface and by a white surface.

The student painted the bulb of one thermometer black and the bulb of another thermometer white.

Figure 3 shows some of the equipment used.

This is the method used.

1. Ensure that the initial temperature shown on the thermometers is the same.

2. Switch on the infrared heater.

3. Record the temperature shown on each thermometer every 30 seconds for 5 minutes.

Explain why the distance between the infrared heater and each thermometer should be the same.

The infrared heater was a hazard in this investigation.

Describe the risk to the student and one precaution that the student should have taken.

Figure 4 shows the results.

Explain the conclusion that can be made from the results in Figure 4.

The paint used for the thermometer bulb painted white was a matt white paint.

The investigation was repeated using a thermometer bulb painted with shiny silver paint.

The distance between the thermometer and the heater was the same as in the first investigation.

The room temperature was the same as in the first investigation.

Draw a line on Figure 4 to predict the results for a thermometer painted with shiny silver paint.

Waves transfer energy.

Radio waves are transmitted from a radio station and absorbed by a radio receiver.

What is created in the radio receiver when the radio waves are absorbed?

Tick (✓) one box.

An alpha particle

An alternating current

An ultraviolet wave

An X-ray

Radio waves may be refracted when they travel from one substance into another substance.

Which diagram shows the refraction of a radio wave?

Tick (✓) one box.

When the radio receiver is switched on, a sound wave is produced.

Give two differences between radio waves and sound waves.

Table 4 shows the speed of sound in different substances at two different temperatures.

Give three conclusions about the effect of temperature and the type of substance on the speed of sound waves.

A teacher used a ripple tank to show how varying the frequency affected the wavelength of water waves.

Figure 4 shows the apparatus.

This is the method used.

1. Turn on the lamp.

2. Adjust the power supply so that the wooden bar vibrates with a frequency of 10 Hz to produce waves on the water.

3. Take a photograph of the image of the waves projected onto the white card.

4. Measure the length of 5 waves from the photograph.

5. Calculate the wavelength of 1 wave.

6. Repeat steps 2 to 5 for different frequencies.

The method used by the teacher is better than measuring the length of only 1 wave directly from the white card.

Explain why.

The electromagnetic spectrum is made up of waves with different wavelengths and frequencies.

Draw one line from each type of electromagnetic wave to a use of that type of wave.

A student investigated how the type of surface affects the amount of infrared the surface radiates.

The student used a hollow metal cube.

Four of the surfaces of the cube were different.

This is the method used.

1. Fill the cube with hot water and seal it with a lid.

2. Measure the infrared radiation emitted from each surface using an infrared detector.

Figure 8 shows the equipment used.

Table 2 shows some of the variables in this investigation.

Identify each variable as an independent, dependent or control variable.

Tick (✓) one box in each row on Table 2.

One row has been completed for you.

Table 3 shows the results.

What was the resolution of the infrared detector?

Tick (✓) one box.

What was the range of temperatures recorded?

Complete Figure 9.

You should:

• plot the data from Table 3 as a bar chart

• label each bar.

Give one conclusion that can be made from the results in Table 3.

Which equation links frequency (f), wavelength (λ) and wave speed (v)?

Tick (✓) one box.

A radio wave has:

• a speed of 300 000 000 m/s

• a wavelength of 500 m

Calculate the frequency of the radio wave.

Give the unit.

Choose the unit from the box.