[Music] hey guys how's it going mr mitchell here in this video we're going to go over what you need to know and what you need to be able to do for the waves topic and national five physics now if you want to download your own free copy of the learning outcomes document that we're about to go through then check out my website mr mitchell physics dot co dot uk and within the national five section of the website you'll find the document there so let's get going the sqa split the waves topic for national five physics into three key areas so we have wave parameters and behaviors we have the electromagnetic spectrum and we have refraction of light so we're going to go through each one so for the first one wave parameters and behaviors we need to know that waves transfer energy you should also be able to define at transverse and longitudinal waves so remember transverse waves are ones in which the particles will vibrate at 90 degrees or perpendicular to the direction of travel of the wave whereas longitudinal waves are ones in which the particles vibrate along the same direction as the wave you also need to know that sound is an example of a longitudinal wave and the electromagnetic radiation and water waves are examples of transverse waves so remember electromagnetic radiation is all of your radiation including radial waves infrared microwaves and so on you should also be able to determine the frequency period wavelength amplitude and wave speed for longitudinal and transverse waves so quite often wavelength and amplitude can be determined from a wave diagram that you're given and frequency period and wave speed might be found from doing calculations using equations and that takes us to the next statement so it says use appropriate relationships to solve problems involving wave speed frequency period wavelength distance number of waves and time so you need to be able to use all four of these equations comfortably so we've got distance equals speed times time the wave equation v equals f lambda we've got t equals one over f relating the period and the frequency and we've got the equation f equals n over t relating frequency number of waves and time moving on you need to know that diffraction occurs when waves pass through a gap or around an object so that's just the definition of the fraction which is the bending of waves through a gap or around an object you also need to compare long wave and short wave diffraction so what this means is how is diffraction affected if we're using long wavelength waves or short wavelength waves so you should remember that longer wavelength waves have greater diffraction than shorter wavelength waves so longer wavelengths diffract more than shorter wavelengths lastly for section one it says to draw diagrams using wavefronts remember they were just straight lines to show diffraction when waves pass through a gap or around an object and remember we did that in the worked example video for diffraction and wavelength section two is the electromagnetic spectrum and it says to know the relative frequency and wavelength of bands of the electromagnetic spectrum so this doesn't mean that you need to know exact values and exact numbers of typical frequencies and wavelengths but what you do need to know is how the wavelength and frequency are related and at what ends of the spectrum will be higher wavelength and at what ends of the spectrum will be lower wavelength and what ends of the spectrum will be high frequency and low frequency so remember that radial waves have the highest wavelength and gamma rays have the highest frequency but radial waves would have the lowest frequency and gamma rays would have the lowest wavelength next it says to know of typical sources detectors and applications for each band in the electromagnetic spectrum so it's probably a good idea to try and remember one or two sources detectors and applications for each type of radiation as questions relating to these often come up in the exam and lastly for section two it says to know that all radiations in the electromagnetic spectrum are transverse and travel at the speed of light three times ten to the eight meters per second so remember that if you see calculation questions talking about electromagnetic radiation then you should straight away be thinking that the speed of the electromagnetic waves in that question are gonna be the speed of light three times ten to the eight meters per second and they won't always give you that number lastly we have refraction of light and it says here that you need to know that refraction occurs when waves pass from one medium to another so medium just means the type of material like air or glass or water for example next it says to describe refraction in terms of change of wave speed change in wavelength and change of direction where the angle of instance is greater than zero degrees for waves passing into both a more dense and the less dense medium so breaking this up into parts first of all describe refraction in terms of wave speed that's just your definition of refraction so remember refraction is the change in speed of a wave as it passes from one material to another change in wavelength so remember that if we're going from a less dense medium into a more dense medium like from air to glass then our wavelength will decrease and if we're going from a more dense medium to a less dense medium our wavelength will increase and next it says a change of direction so remember that light is only going to change direction when it strikes an object at an angle of instance greater than zero degrees because when it passes along the normal it's just gonna pass straight through so for that reason we could not define refraction as a change in direction of light it's got to be the change in speed of light and also remember for light going from a less dense medium to a more dense medium like from air to glass then your light will refract or bend towards the normal whereas if the opposite is true if it's going from a more dense medium to a less dense medium like from glass back into air then the light will refract or bend away from the normal and lastly it says here to identify the normal angle of instance and angle of refraction in ray diagrams showing refraction so you need to be able to identify these points on diagrams maybe label the diagrams but also possibly draw the ray diagrams yourself you should also be able to determine angles of instance and angles of refraction from given diagrams that's all from me folks i hope you found the video useful if you did give it a thumbs up subscribe and i'll see you in the next one take care you