AQA GCSE Physics Physics Paper 2 (Foundation), June 2025: Question 8

Thunderstorm Waves: Light, Sound, and Wave Speed

📋 What This Question Tests

This question assesses core knowledge of Wave Properties and Motion Calculations:

Comparing wave types: Identifying key differences and similarities between electromagnetic (transverse) waves and mechanical (longitudinal) sound waves.
Equation recall: Selecting the correct formula linking speed, distance, and time.
Quantitative physics skills: Rearranging an equation to calculate the travel time of a sound wave.

Question 08.1 (6 Marks)

Describe the similarities and differences between visible light waves and sound waves.

✅ Model Answer Points

Differences (aim for at least 3):

Light is a transverse wave; sound is a longitudinal wave.
Light is an electromagnetic wave; sound is a mechanical wave.
Light can travel through a vacuum; sound requires a medium (particles) to travel.
Light travels much faster (3 × 10⁸ m/s in air) than sound (~330 m/s in air).
Sound travels faster in solids than air, whereas light travels slower in dense media/solids than in air.
Visible light has a higher frequency and shorter wavelength compared to sound waves.

Similarities (aim for at least 2):

Both transfer energy without transferring matter.
Both can undergo reflection, refraction, and diffraction.

🧠 Exam Technique (Level-Marked Question)

To secure Level 2 (4–6 marks):

You must include both similarities and differences. Discussing only differences will cap your response at Level 1 (maximum 3 marks).
Pair your comparative points clearly using comparative connectives like "whereas" or "in contrast to" (e.g., "Sound waves are longitudinal, whereas light waves are transverse").
Group points logically under subheadings: Similarities and Differences.

💡 Key Properties Summary Table

Property	Visible Light	Sound Waves
Wave Type	Transverse	Longitudinal
Classification	Electromagnetic	Mechanical
Needs a Medium?	No (travels in vacuum)	Yes (needs particles)
Speed in Air	~300 000 000 m/s	~330 m/s

❌ Common Errors to Avoid

Mixing up transverse and longitudinal: Thinking sound is transverse because it travels through the air like light.
Vague statements: Writing "they have different speeds" without stating which one is faster.
Forgetting similarities: Focusing purely on differences and missing easy marks for reflection, refraction, and energy transfer.

Marking Guide: Level 2 (4–6 marks) requires scientifically relevant facts given in clear detail covering both similarities and differences. Level 1 (1–3 marks) contains isolated facts without clear comparative relevance.

Question 08.2 (1 Mark)

Which equation links distance (s), speed (v) and time (t)? Tick (✓) one box.

✅ Correct Answer

Tick the second box:

speed = distance / time

In standard symbols: v = s / t

🧠 Exam Tip

Check the units if you are unsure: Speed is measured in metres per second (m/s), which tells you that metres (distance) is divided by seconds (time).
In physics, s represents distance or displacement (from the Latin spatium), not speed!

Question 08.3 (3 Marks)

Calculate the time taken for sound created by a lightning strike 13 200 m away to reach the student (speed of sound in air = 330 m/s).

📐 Step-by-Step Calculation

Identify variables & formula:
Distance ( s ) = 13 200 m
Speed ( v ) = 330 m/s
Formula: speed = distance / time
Substitute the numbers into the equation:
330 = 13 200 / t [1 mark]
Rearrange to solve for time (t):
t = 13 200 / 330 [1 mark]
Calculate final value:
t = 40 s [1 mark]

❌ Common Calculation Traps

Rearrangement blunder: Calculating 330 / 13 200 (giving 0.025 s) or multiplying them together ( 13 200 × 330 ). Always substitute first before rearranging.
Using speed of light: Make sure you read carefully—the question asks for the arrival of the sound, so use 330 m/s, not the speed of light.
Omitting intermediate steps: Always write the substitution step. If you make a calculator mistake, you can still gain 2 out of 3 marks for correct working.

Mark Breakdown:
• Mark 1: Correct substitution: 330 = 13 200 / t or 13 200 = 330 × t
• Mark 2: Correct rearrangement: t = 13 200 / 330
• Mark 3: Correct final answer: 40 (unit seconds is already given on the answer line).