IP Physics Notes (Upper Secondary, Year 3-4): 8) Waves

Study guide30 Sep 2025, 00:00 ZUpdated 30 Nov 2025

Review EM spectrum properties, mechanical wave terms, sound/ultrasound, and CRO measurements for IP Year 3-4.

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Q: What does IP Physics Notes (Upper Secondary, Year 3-4): 8) Waves cover?
A: Review EM spectrum properties, mechanical wave terms, sound/ultrasound, and CRO measurements for IP Year 3-4.

Quick recap -- Waves transport energy without carrying matter. Understand the language (wavelength, frequency, period), track phase with wavefronts, and apply the same maths from microwaves to ultrasound echoes.

The core idea is simple: Waves transfer energy without transferring matter overall.

Use it as a working check: Know wavelength, frequency, period, amplitude, and speed. Frequency stays fixed when waves cross a boundary, while speed and wavelength can change.

Then go one layer deeper: Use the EM spectrum, sound, ultrasound, and CRO sections to practise matching a wave type to its equation, graph reading, use, and hazard.

Keep your practice loop tight via our IP Physics tuition hub-it links each topic here to quizzes, diagnostics, and WA-style problem sets.

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These notes align with SEAB GCE O-Level Physics (6091) content used in IP programmes (exams from 2026).

Status: SEAB O-Level Physics 6091 syllabus (exams from 2026) checked 2025-11-30 - scope unchanged; remains the reference for these notes.

Electromagnetic Spectrum

EM waves are transverse oscillations of electric and magnetic fields and travel at $c = \pu{3.00 \times 10^8 m.s-1}$

Reviewed by

Chee Wei Jie·Academic Advisor (Physics)

Situation	What changes together	How to use it in answers	Common trap
Moving from radio toward gamma	Wavelength decreases, while frequency and photon energy increase.	Higher-frequency EM waves are more likely to be ionising and need stricter shielding.	Saying gamma travels faster than radio in vacuum.
Entering glass, water, or another medium	Speed and wavelength change; frequency stays the same.	Use the unchanged frequency with the new speed to reason about the new wavelength.	Changing frequency to explain refraction.
Choosing a use	Match the property to the task: heating, imaging, communication, sterilisation, or therapy.	Name the property, then the application, such as penetration for X-ray imaging.	Listing a use without linking it to absorption or penetration.
Comparing hazards	Higher-frequency ultraviolet, X-ray, and gamma radiation can damage cells because their photons carry more energy.	Mention exposure control, shielding, or limiting dose when the question asks about safety.	Treating visible light and ultraviolet as the same hazard.

Graph shown	Horizontal spacing between matching crests gives	Next calculation	Common trap
Displacement-time graph	Period $T$	Find frequency using $f = 1/T$ .	Calling the crest spacing wavelength just because the graph looks like a wave.
Displacement-distance graph	Wavelength $\lambda$	Use $v = f\lambda$ if frequency is known.	Using $1/\lambda$ as the frequency.
CRO trace	Period from horizontal divisions times time-base	Convert milliseconds to seconds, then use $f = 1/T$ .	Treating divisions as seconds without applying the time-base.

Wave type	Oscillation direction	Wave travel direction	Example	Common trap
Transverse mechanical wave	Perpendicular to travel	Along the rope, surface, or wavefront direction	A rope wave moving right while the rope moves up and down	Saying the rope particles move right with the wave.
Longitudinal mechanical wave	Parallel to travel	Along the line of compressions and rarefactions	Sound travelling right while air particles vibrate left and right	Drawing crests and troughs instead of compressions and rarefactions.
Electromagnetic wave	Field oscillations are perpendicular to travel	Direction of energy transfer	Light travelling forward without needing air particles	Calling EM waves longitudinal because they can travel through space.

Boundary change	Speed in new medium	Wavelength in new medium	Direction of refraction	Common trap
Enters a slower medium	Decreases.	Decreases because $\lambda = v/f$ and $f$ is unchanged.	Bends toward the normal.	Saying the frequency decreases to fit the shorter wavelength.
Enters a faster medium	Increases.	Increases because $\lambda = v/f$ and $f$ is unchanged.	Bends away from the normal.	Drawing the bend correctly but explaining it using a changing frequency.
Hits a straight barrier and reflects	Speed stays the same in the same medium.	Wavelength stays the same in the same medium.	Angle of incidence equals angle of reflection.	Measuring the angles from the surface instead of from the normal.

What the question asks for	Read from the screen	Multiply by	Finish with
Peak voltage	Centre line to crest in vertical divisions	Y-gain	Report voltage.
Peak-to-peak voltage	Trough to crest in vertical divisions	Y-gain	Divide by 2 only if the question asks for peak voltage.
Period	One full cycle in horizontal divisions	Time-base	Use $f = 1/T$ for frequency.

IP Physics Notes (Upper Secondary, Year 3-4): 8) Waves

Electromagnetic Spectrum

EM Spectrum Comparison Checkpoint

Wave Terminology & Equation

Wave graph reading checkpoint

Transverse vs Longitudinal Waves

Particle motion direction checkpoint

Reflection & Refraction of Wavefronts

Boundary-change direction checkpoint

Sound Waves

Ultrasound & Applications

Cathode Ray Oscilloscope (CRO)

CRO Reading Checkpoint

Worked Example: Determining Sound Speed

Practice Quiz

Key Takeaways

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