Transverse and longitudinal waves

A pair of sunglasses has lenses that absorb all ultraviolet and some visible light.

Ultraviolet and visible light are both transverse waves.

What is meant by ‘transverse waves’?

Ultraviolet can cause sunburn and eye damage.

Give one other risk to health from exposure to ultraviolet.

Complete the sentence.

Compared with the wavelength of visible light, the wavelength of ultraviolet

A wave of visible light has a frequency of 6.25 × 10¹⁴ Hz.

Calculate the wavelength of this light.

Use the Physics Equations Sheet.

Give your answer in nanometres (nm).

A ray of visible light incident on the lens in a pair of sunglasses is refracted.

Figure 3 shows a wave front diagram for visible light incident on the lens.

For each wave front, one end of the wave front enters the lens before the other end.

Explain why the light refracts as it enters the lens.

Figure 4 shows a ray of visible light incident on glass.

The angle of incidence is 45°.

The angle of refraction of the ray in the glass is 28°.

Complete the ray diagram in Figure 4 to show the path of the ray in the glass.

You should:

• draw the normal line

• draw the refracted ray in the glass.

You do not need to draw the ray leaving the glass.

Figure 6 shows an electronic whistle used by a referee in a football match.

When the button is pressed the whistle emits sound waves that travel through the air.

What is transferred by the sound waves as they travel through the air?

Tick () one box.

What is a typical value for the speed of sound in air?

Tick () one box.

The whistle can emit two different sound waves, A and B.

Figure 7 shows the two different sound waves as displayed on a screen.

The sound waves are drawn to the same scale.

Complete the sentences to describe a difference and a similarity between the two waves.

Choose answers from the box.

Difference

Similarity

Wave A has a frequency of 4.0 kHz.

Which of the following is the same as 4.0 kHz?

Tick () one box.

Calculate the period of wave A.

Use your answer from Question 03.4 and the equation:

Sound waves in air are longitudinal waves.

Complete the sentence to describe a sound wave.

Choose answers from the box.

When sound waves travel through air they create areas

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.

Sound waves are longitudinal waves.

Figure 9 shows a sound wave.

Complete the labels on Figure 9. Choose answers from the box.

Which of the following is true for longitudinal waves? Tick (✓) one box.

Figure 10 shows a device a farmer uses to scare away birds.

The device emits a very loud sound. The farmer measures the sound emitted by the device at different distances from the device.

Figure 11 shows a visual display of the sound waves at different distances from the device. Both waves are drawn to the same scale.

Which property of the wave changes between 80 m and 200 m? Tick (✓) one box.

Figure 12 shows how the speed of the sound emitted by the device is affected by the

temperature of the air.

The farmer tests the device on a day when the temperature of the air is 15 °C. What is the speed of the sound emitted by the device when the temperature of the air is 15 °C?

The farmer stands a safe distance from the device. It takes a time of 0.20 s for the sound to travel from the device to the farmer. Calculate the distance between the device and the farmer. Use your answer to Question 04.4 and the equation: distance = speed × time

Explain how the time taken for the sound to reach the farmer is affected by the temperature of the air. Use Figure 12.

A teacher used a ripple tank to demonstrate water waves. The teacher used a lamp to project a shadow of the water waves onto a screen below the ripple tank.

Figure 4 represents the shadow of the water waves seen on the screen.

1.0 mm on Figure 4 represents 5.0 mm on the screen. Determine an accurate value for the wavelength of the waves on the screen. Give your answer in mm. Show how you work out your answer.

The teacher adjusted the frequency of the waves produced in the ripple tank.

The teacher measured the wavelength five times. Table 2 shows the results.

Calculate value X in Table 2.

The teacher states that the results are very precise. Which of the following supports the statement made by the teacher? Tick (✓) one box.

Describe the difference between longitudinal waves and transverse waves.

Figure 8 shows a longitudinal wave.

What do the labels A and B on Figure 8 represent? Choose answers from the box.

The wave shown in Figure 8 has a frequency of 4.0 kHz Calculate the period of the wave. Use the Physics Equations Sheet. Give the unit.

Sound waves are longitudinal. Figure 9 shows how the speed of sound varies with the temperature of the air.

Use the Physics Equations Sheet to answer questions 06.3 and 06.4.

Write down the equation that links frequency (f), wavelength (λ) and wave speed (v).

A sound wave with a frequency of 300 Hz travels through the air. The air has a temperature of 28.0 °C

Determine the wavelength of the sound wave. Use Figure 9.

Figure 1 shows a longitudinal wave.

What do the labels A and B on Figure 1 represent? Choose answers from the box.

The wave shown in Figure 1 has a frequency of 4.0 kHz Calculate the period of the wave. Use the Physics Equations Sheet. Give the unit.

Sound waves are longitudinal. Figure 2 shows how the speed of sound varies with the temperature of the air.

Use the Physics Equations Sheet to answer questions 01.3 and 01.4.

Write down the equation that links frequency (f), wavelength (λ) and wave speed (v).

A sound wave with a frequency of 300 Hz travels through the air. The air has a temperature of 28.0 °C

Determine the wavelength of the sound wave. Use Figure 2.

Figure 11 shows the equipment a teacher used to determine the speed of a water wave.

The equipment includes:

• a ripple tank filled with water

• a wooden bar that creates ripples on the surface of the water

• a light source which causes a shadow of the ripples on the screen.

Describe how equipment in Figure 11 can be used to measure the wavelength, frequency and speed of a water wave.

The teacher put a plastic duck in the ripple tank as shown in Figure 12.

The plastic duck moved up and down as the waves in the water passed.

How does the movement of the plastic duck in Figure 12 demonstrate that water waves are transverse?

The teacher measured the maximum height and the minimum height of the plastic duck above the screen as the wave passed.

The teacher repeated his measurements.

Table 4 shows the teacher’s measurements.

Calculate the mean amplitude of the water wave.

Figure 3 shows the equipment a teacher used to determine the speed of a water wave.

The equipment includes:

• a ripple tank filled with water

• a wooden bar that creates ripples on the surface of the water

• a light source which causes a shadow of the ripples on the screen.

Describe how equipment in Figure 3 can be used to measure the wavelength, frequency and speed of a water wave.

The teacher put a plastic duck in the ripple tank as shown in Figure 4.

The plastic duck moved up and down as the waves in the water passed.

How does the movement of the plastic duck in Figure 4 demonstrate that water waves are transverse?

The teacher measured the maximum height and the minimum height of the plastic duck above the screen as the wave passed.

The teacher repeated his measurements.

Table 2 shows the teacher’s measurements.

Calculate the mean amplitude of the water wave.

Figure 2 shows a slinky spring used to model a sound wave.

Label the arrows on Figure 2

Choose the answers from the box.

What type of wave is a sound wave?

Tick one box.

Figure 3 shows two students measuring the speed of sound in air.

One student bangs two bricks together.

The sound wave produced is reflected from the wall and travels back to the students.

Describe how they can determine the speed of sound.

A car aerial receives radio waves from a radio transmitter. Radio waves are transverse waves. Sound waves are longitudinal waves.

Describe the difference between transverse waves and longitudinal waves.

The radio waves have a frequency of 4.8 × 10⁹ Hz Wave speed of electromagnetic waves = 3.0 × 10⁸ m/s Calculate the wavelength of the radio waves. Give your answer to 2 significant figures.

Describe how the radio waves reaching the car aerial produce signals in the electrical circuit of the car radio.