Cheatography

# waves Cheat Sheet by sams sub

physics waves revision

### key words

 amplitude is half of the distance between a waves high point crest and low point trough. Amplitude measures how much a wave is displaced from its resting point. wavelength is measured from a point on one wave to the same point on the next wave and is written as λ (Greek letter for lamba). The difference in colours is caused by different wavele­ngths of light. Red has the longest wavelength in the rainbow while purple has the shortest oscill­ation an up-and­-down or back-a­nd-­forth motion vacuum space that has no matter in it frequency the number of waves that pass a fixed point in a given unit of time is written as f node the node of a wave is where the wave doesn't move antinode the part of the wave where it moves the most away from the centre wave speed is the speed at which the energy is transf­erred through the medium transverse Wave are when the oscill­ations are perpen­dicular to the direction of the waves advance longit­udinal wave are when the displa­cement is parallel to the direction of the wave overtone generally applied to any higher­-fr­equency standing wave fundam­ental the frequency at which the entire wave vibrates stationary waves when two waves are moving at the same time in opposite direct­ions, both having the same amplitude and frequency Displa­cement how far the quantity that is in oscill­ation has moved from its mean Period time taken for a wave to pass electr­oma­gnetic is a continuous range of wavele­ngths electro contains electric energy magnetic contains magnetic distur­bance** phase difference The difference in phase angle of two different waves with the same frequency

### equations

 frequency = 1/time or time = freque­­ncy/1 f=1/t or T=f/1 speed= frequency x wavelength v=f x λ wavespeed = frequency x wavelength v=f x λ

### electr­oma­gnetic spectrum

 uses dangers radio waves (3x109) Teleco­mmu­nic­ation, TV, radio None microwaves (3x1012) Cooking, teleco­mmu­nic­ation, RADAR None infra red radiation (4x1014) Heating, cooking, TV remotes, night vision Can burn visible light (10-6) photog­raphy, illumi­nation erythema, pigmen­­ta­tion, thermal damage, free radical, production ultra violet (10-9) killing bacteria, creating fluore­scent effects, curing inks and resins, photot­­he­rapy, sun tanning, security skin cancer, premature ageing X-rays (10-6) looks at bones causes cancer gamma rays (10-4) radio therapy, steril­isation and disinf­ection, nuclear industry Causes cancer

### the laws of refraction

 Light waves (or electr­oma­gnetic radiation of other freque­ncies) travel best in a vacuum (a space without any matter in it) When the waves have to travel through solid, opaque materials, their movement IS STOPPED by the electronic charges of the atoms and molecules around them e.g Metals that are full of freely moving electrons stop the oscill­ations completely and so the light wave energy is reflected back – metals therefore look shiny and make good mirrors. Some waves are absorbed in solids, with certain waves being reflected back so that we are able to see colours In transp­arent materials (water, glass and many plastics) the waves are NOT STOPPED or ABSORBED but they are slowed down

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