GCSE Physics resources
AQA GCSE Waves
Sound moves through vibrating matter. Ultrasound and seismic evidence use the travel, reflection and transmission of vibrations to infer hidden boundaries.
Start here
Sound moves through vibrating matter. Ultrasound and seismic evidence use the travel, reflection and transmission of vibrations to infer hidden boundaries.
Before you revise
Choose an answer from memory. Your result tells you what to watch for in the guide.
Core revision guide
Sound moves through vibrating matter. Ultrasound and seismic evidence use the travel, reflection and transmission of vibrations to infer hidden boundaries.
Scope: 8463 Physics only · Higher only
Alternating pressure in air makes the eardrum vibrate. Vibrations transfer through middle-ear bones into inner-ear fluid, where sensory structures convert them to nerve signals. This conversion has a limited frequency response; normal human hearing is roughly 20 Hz to 20 kHz. Ultrasound is above 20 kHz. Larger amplitude gives stronger vibration/loudness; higher frequency gives higher pitch.
Scope: 8463 Physics only · Higher only
A pulse partly reflects at boundaries between materials. The time records the outward and return journeys: depth d = vt/2. In tissue at 1500 m/s, a 200 microsecond echo gives 1500 × 200 × 10⁻⁶/2 = 0.15 m, a plausible 15 cm depth. An echo time of 0.020 s would imply 15 m, which is unsuitable as an ordinary tissue-depth example.
Scope: 8463 Physics only · Higher only
Earthquakes produce longitudinal P waves that travel through solids and liquids and transverse S waves that cannot pass through liquids. Observed S-wave absence and refracted P-wave paths supply evidence for a liquid outer core and hidden internal boundaries. These are conclusions from wave data, not direct photographs of the core.
Misconception clinic
Read each belief, say what is wrong with it, then compare your correction.
Tempting idea: 0.30 m.
Use instead: 0.30 m is the round-trip distance. 1500 × 0.000200/2 = 0.15 m.
Tempting idea: All waves must stop at every boundary.
Use instead: P waves may transmit and refract. Transmission property connects observation to structure.
Retrieval practice
Worked examples
Apply ear and hearing limits in the worked reasoning, then try the changed-context questions below.
Scope: 8463 Physics only · Higher only
Depth = 0.15 m = 15 cm, plausible for a tissue boundary.
Exam precision
Do this: Follow the vibration chain or evidence chain requested. For ultrasound echoes use half the travelled distance to locate the reflecting boundary.
Independent practice
Write an answer before opening the marking guidance. Then edit the exact phrase or step that would gain the next mark.
Scope: 8463 Physics only · Higher only
Original PhysicsUK mark scheme: Point 1 (1 mark): d = vt/2 because the path is out and back. Point 2 (1 mark): t = 160 × 10⁻⁶ s; d = 1500 × 0.000160/2. Point 3 (1 mark): d = 0.12 m = 12 cm. Award each distinct point once. Accept equivalent scientifically correct wording. No half marks.
Model answer: d = vt/2 because the path is out and back. t = 160 × 10⁻⁶ s; d = 1500 × 0.000160/2. d = 0.12 m = 12 cm.
Acceptable answers: Expected result: d = 0.12 m = 12 cm. Accept the unrounded value or a correctly rounded equivalent to two or more significant figures; accept equivalent units if converted correctly. No additional measurement interval is implied.
Marking notes: Method marks remain available after an arithmetic error. Carry an earlier numerical error into a later valid step; award that method point if the unit conversion and physics are correct. A fully correct answer with unit earns all marks unless working is expressly requested.
Scope: 8463 Physics only · Higher only
Original PhysicsUK mark scheme: Point 1 (1 mark): Air pressure variations make the eardrum vibrate. Point 2 (1 mark): Vibration is transmitted through middle-ear structures to inner-ear fluid/sensory cells. Point 3 (1 mark): Sensory structures convert vibration into nerve signals interpreted as sound. Award each distinct point once. Accept equivalent scientifically correct wording. No half marks.
Model answer: Pressure variations vibrate the eardrum; the vibration reaches the inner ear, whose sensory structures produce nerve signals.
Questions pupils ask
The measured delay includes travel to the reflecting boundary and back, so speed times time is twice the one-way depth.
Useful next steps