IGCSE›Edexcel IGCSE Physics›Mind mapsWaves & The Electromagnetic SpectrumEdexcel IGCSE Physics: Mind mapStudy pack PDFAlso for this subtopic:Revision notesFlashcardsSubtopic testCover factsWhat is a wave?Transfers energy and information, not matterTransverse: vibrations at 90° to travelLongitudinal: vibrations parallel to travelAmplitude: maximum displacement from restFrequency: waves per second, in HzWavelength: crest to next crestWave equationsv=f×λv = f \times \lambdav=f×λf=1Tf = \frac{1}{T}f=T1Period: time for one cycle50 Hz and 4 m gives 200 m/sAll waves can be reflected and refractedDoppler effectSource moving relative to observerTowards: higher frequency, shorter wavelengthAway: lower frequency, longer wavelengthAmbulance siren pitch changesWaves & EMthe spectrumv=fλv = f\lambdav=fλHzmEM spectrumRadio, micro, infrared, visible, UV, X-ray, gammaFrequency increases along the listAll travel at the same speed in a vacuumRed has the longest visible wavelengthUses and dangersMicrowaves: cooking; heat tissue internallyInfrared: heaters; skin burnsUV: fluorescent lamps; surface cell damageX-rays: imaging; gamma: sterilising, cancer riskExam tipsNever say waves transfer matterLearn the spectrum order with a mnemonic