AQA GCSE Combined Science: Trilogy Physics Paper 2 (Foundation), 2022: Question 6

11 marks · Standard Demand difficulty · Short Answer

Identify features of a longitudinal wave and calculate wave period and wavelength using a speed-temperature graph and the wave equation.

Practise this question

Question

The image shows an exam question about longitudinal waves. Figure 8 illustrates a longitudinal wave using dots to represent particles, with labels A pointing to a spread-out region (rarefaction) and B indicating the distance between two compressed regions (wavelength). Question 06.2 asks for a period calculation given a frequency of 4.0 kHz. Figure 9 is a line graph showing the speed of sound in m/s increasing linearly with temperature from 0 to 50 degrees Celsius. Question 06.4 requires determining the wavelength of a 300 Hz sound wave at 28.0 degrees Celsius using the graph.
Question text

06 Figure 8 shows a longitudinal wave.

Figure 8

06.1 What do the labels A and B on Figure 8 represent?

Choose answers from the box.

[2 marks]

amplitude frequency rarefaction reflection wavelength

A

B

06.2 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.

[4 marks]

*18* 20

Period = Unit

Sound waves are longitudinal.

Figure 9 shows how the speed of sound varies with the temperature of the air.

Figure 9

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

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

[1 mark]

06.4 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.

[4 marks]

Wavelength = m

Mark scheme

Show the mark scheme The mark scheme table lists the correct answers and marking points. For 06.1, A is rarefaction and B is wavelength. For 06.2, it shows converting 4.0 kHz to 4000 Hz, applying T = 1/f to get 0.00025, and identifying the unit as seconds. For 06.3, the equation is wave speed = frequency x wavelength. For 06.4, it shows reading v = 348 m/s from the graph, substituting into the equation (348 = 300 x wavelength), and calculating the final answer as 1.16 m.

Question 6

AO /

Question Answers Extra information Mark

Spec. Ref.

06.1 A = rarefaction 1 AO1

6.6.1.1

B = wavelength 1

AO /

Spec. Ref.

06.2 f = 4000 Hz 1 AO2

1 allow a correct substitution using 1 AO2

T = 4000

an incorrectly / not converted

value of f

T = 0.00025 allow a correct calculation using 1 AO2

an incorrectly / not converted

value of f

seconds or s 1 AO1

6.6.1.2

AO /

Spec. Ref.

06.3 wave speed = frequency × 1 AO1

wavelength 6.6.1.2

or

v = f λ

AO /

Spec. Ref.

06.4 v = 348 allow a value in the range 347 to 1 AO2

348 6.6.1.2

subsequent marks may only be

awarded if value for v is in the

range 343 to 349

348 = 300 × λ allow a correct substitution using 1

an incorrect value of v read from

graph

348 allow a correct rearrangement 1

λ =

using an incorrect value of v

read from graph

1.16 (m) allow 1.2 (m) 1

allow a correct calculation using

an incorrect value of v read from

graph

allow a maximum of 2 marks for

use of v = 330 m/s

Total Question 6 11

How to answer it

Properties and Calculations of Longitudinal Waves

What this question tests

This question assesses your ability to identify features of a longitudinal wave, convert units (kHz to Hz), calculate the period of a wave, recall the wave speed equation, and extract data from a graph to perform multi-step calculations.

Part 06.1

Identifying Wave Features

Correct Answers

  • A: rarefaction
  • B: wavelength

Key Knowledge

In a longitudinal wave (like sound):

  • Compressions are regions where particles are bunched together.
  • Rarefactions are regions where particles are spread apart.
  • Wavelength is the distance from one point on a wave to the equivalent point on the next (e.g., compression to compression).
Part 06.2

Calculating the Period

Calculation Steps

  1. Convert Frequency: 4.0 kHz = 4000 Hz
  2. Identify Equation: Period = 1 / frequency
  3. Substitute: T = 1 / 4000
  4. Final Answer: 0.00025
  5. Unit: seconds (or s)

Common Errors

  • Unit Conversion: Many students forget that "k" (kilo) means 1000. Using 4.0 instead of 4000 leads to an incorrect answer.
  • The Unit: Period is a measurement of time, so the unit must be seconds.
Total: 4 Marks (1 for conversion, 1 for substitution, 1 for calculation, 1 for unit)
Part 06.3

The Wave Equation

Correct Equation

wave speed = frequency × wavelength

OR

v = f λ

Exam Technique

Always write the equation in words or standard symbols. If you use symbols, ensure they are correct (λ for wavelength, not w).

Part 06.4

Using Graphical Data

Step-by-Step Solution

  1. Read the Graph: At 28.0 °C, follow the line up to the curve and across to the y-axis. The speed (v) is 348 m/s.
  2. Substitute into Equation: 348 = 300 × λ
  3. Rearrange: λ = 348 / 300
  4. Calculate: λ = 1.16 m

Examiner Insight

Top-level responses used a ruler to find the exact value on the graph. The mark scheme allows a small range (347 to 348 m/s), but being precise is key. Even if you misread the graph slightly, you can still earn "Error Carried Forward" marks for the calculation if your method is correct.

Calculation Traps

Rearranging: A common mistake is multiplying the speed and frequency. Remember: to find wavelength, you must divide speed by frequency.

Visual Summary

Longitudinal Wave Diagram

If asked to draw this, you should show:

  • Vertical lines or dots.
  • Areas where lines are very close together (Compressions).
  • Areas where lines are far apart (Rarefactions).
  • The wavelength arrow should go from the center of one compression to the center of the next.

Topics

Physics · P6: Waves

Question and mark scheme from the AQA GCSE Combined Science: Trilogy examination, Physics Paper 2 (Foundation), 2022. QuestionVault is an independent revision resource; questions remain the copyright of the awarding body.