Transverse and longitudinal waves

Figure 2 shows the position of air particles in the path of a sound wave.

What do the labels P and Q represent?

Choose the answers from the box.

Sound waves are longitudinal waves.

What direction are the oscillations in a longitudinal wave?

Tick () one box.

At 45° to the direction of energy transfer

Parallel to the direction of energy transfer

Perpendicular to the direction of energy transfer

A teacher and a student made measurements to determine the speed of sound in air.

They used a device called a ‘starter pistol’.

A starter pistol makes a loud sound and produces a puff of smoke at the same time.

Figure 3 shows the teacher and the student 100 m apart.

This is the method used.

1. The teacher fires the starter pistol.

2. The student sees the puff of smoke and starts the stopwatch.

3. The student hears the sound from the starter pistol and stops the stopwatch.

4. The student records the time on the stopwatch.

Why did the student see the puff of smoke before hearing the sound?

The teacher and student repeated the experiment several times and calculated a mean value for the times recorded.

The mean value for the time was used to calculate the speed of sound in air.

Why is it good practice to calculate a mean value in an investigation?

Tick () one box.

To reduce the effect of random errors

To reduce the effect of systematic errors

To reduce the effect of zero errors

The sound wave produced had a wavelength of 0.12 m and a wave speed of 330 m/s.

Calculate the frequency of the sound wave.

Use the equation:

Choose the unit from the box.

Figure 3 shows a ripple tank used to investigate the behaviour of water waves.

Describe a method a student could use to determine the frequency of the water waves.

Use the Physics Equations Sheet to answer Questions 03.3 and 03.4.

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

Tick (✓) one box.

v = f λ

v = f² λ

Figure 4 shows the water waves in the ripple tank when viewed from above.

Figure 4 has been drawn to actual size.

The water waves have a frequency of 2.5 Hz.

Calculate the wave speed of the waves in Figure 4.

You should take measurements from Figure 4.

A student used a ripple tank to investigate water waves.

What type of wave is a water wave?

Tick (✓) one box.

A sound wave

A transverse wave

An electromagnetic wave

Figure 8 shows the ripple tank.

Describe how the water waves are produced in the ripple tank.

The student counted the number of waves reaching the end of the tank.

What other measurement is needed to calculate the frequency of the waves?

Figure 9 shows three different wave patterns produced on the white card.

Which pattern in Figure 9 shows the waves with the greatest frequency?

Give a reason for your answer.

Tick (✓) one box.

A B C

Another student investigated how the depth of water in a tray affected the speed of water waves.

Figure 10 shows the apparatus.

This is the method used.

1. Pour water at room temperature into a tray to a depth of 5 mm.

2. Lift one end of the tray 5 cm and then let it go.

3. Measure the time taken for the water wave to move across the tray.

4. Calculate the speed of the water wave.

5. Repeat steps 1 to 4 with different depths of water.

Give one control variable in the student’s investigation.

The student calculated the speed of the waves at each depth.

Figure 11 shows the results.

Draw a line of best fit on Figure 11.

What is the speed of the water wave when the depth of the water is 20 mm?

Use Figure 11.

Speed of water wave = __________________ metres per second

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?

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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.

Figure 1 shows a transverse wave.

Which arrow shows the amplitude of the wave?

Tick (✓) one box.

Which arrow shows the wavelength of the wave?

Tick (✓) one box.

A teacher demonstrated waves on a string.

Figure 2 shows the apparatus used.

This is the method used.

1. Switch on the signal generator and vibration generator so the string vibrates up and down.

2. Move the wooden bridge until a clear wave pattern is formed between the wooden bridge and the vibration generator.

3. Use a metre rule to measure the length of the string between the wooden bridge and the vibration generator.

4. Record the frequency of the wave from the signal generator.

5. Record the number of loops in the wave pattern. The wave pattern shown in Figure 2 has one loop.

6. Change the frequency on the signal generator until a new wave pattern is formed.

7. Repeat steps 4 to 6.

Give one control variable in this demonstration.

The length of the string between the vibration generator and the wooden bridge was about 1.5 m

The teacher used a metre rule to measure the length of the string.

Suggest two reasons why making an accurate measurement was difficult.

Table 1 shows the results.

Give one conclusion about frequency and wavelength from the data in Table 1.

Each loop of the wave pattern is the length of half a wavelength.

Determine wavelength X in Table 1.

Calculate the period of the wave when the frequency was 30 Hz

Give your answer to 2 significant figures.

Use the Physics Equations Sheet.

Two 18-year-old male students measured their reaction times.

The students used two methods, Method 1 and Method 2.

Method 1

1. Sit in front of a tablet computer.

2. When the tablet makes a sound, touch the tablet screen as quickly as possible.

3. Record the reaction time shown on the tablet.

4. Repeat steps 1 to 3 another two times.

Method 2

1. Hold a metre rule so the bottom of the rule is level with the top of the other student’s thumb.

2. Let go of the metre rule.

3. The other student catches the metre rule.

4. Record the position of the student’s thumb on the metre rule.

5. Convert the position on the metre rule to a reaction time using a conversion table.

6. Repeat steps 1 to 5 another two times.

Table 4 shows the results.

Student A and student B had different reaction times.

Suggest two reasons why student A ’s reaction time was longer than student B ’s reaction time.

Give two reasons why Method 1 would give more accurate results than Method 2.

In Method 1 the students react to a sound.

In Method 2 the students react when they see the metre rule drop.

A sound wave is a longitudinal wave.

Visible light is a transverse wave.

Describe the difference between a longitudinal wave and a transverse wave.

The nervous system coordinates reflex actions.

A person accidentally touches a hot object.

The person moves their hand away quickly.

Describe how information about the hot object is detected, and how the information reaches the muscles in the arm.