P6 Waves Flashcards
Definitions
Amplitude
Wavlength
Frequency
Amplitude-maximum displacement of a point on the wave from its undisturbed position
Wavelength- the distance between the same point of 2 adjacent waves
Frequency- number of complete waves passing a certain point per second
Explain
2 types of waves and an example
Transverse- Waves oscillate perpendicular to the direction of energy transfer. An example is all electromagnetic waves
Longitudinal- Waves oscillate parrallel to the direction of energy transfer. An example is sound waves
Period equation
T=1/f
Period(s)= 1/frequency(Hz)
Wave speed equation
v=f x wavelength
Wave speed(m/s)= frequency(Hz) x wavelength(m)
Practical
How to measure wave speed in a liquid
Independent variable- Frequecny of waves
Dependent variable- Wavelength and wave speed
Control variable- Depth of water in ripple tank and shape of ripple tank
Set up ripple tank with a dipper that is attached parralell to the short side of the tank.
Below the ripple tank should be paper so place ruler on top so that wavelength can be measured
Take a photo so that you can count the distance of the wave then use v=f x wavelength to get wave speed
How to measure wave speed in a solid
Suspend solid metal in the air.
Then hit solid with a hammer.
Then measure frequnecy
Then measure object with metre ruler then double that to get wavelength.
Defintion
Angle of incidence
Angle of reflection
Normal
Angle between incoming wave and the normal
Angle between reflected wave and normal
Normal is a line thats perpendicular to the surface
Diffuse
Specular reflection
Specular- When a wave is reflected in a single direction by a smooth surface.
Diffuse- When a wave is reflected by a rough surface and the rays go in different directions.
Makes objects appear matte
Due to the normal being different each time
What increases and decreases across the EM wave spectrum
Increasing frequency
Decreasing wavelength
Order of electromagnetic spectrum
Radio
Microwaves
Infra Red
Visible light
Ultra violet
X rays
Gamma rays
Explain
Refraction
When waves cross boundary between materials at an angle it changes direction and its refracted.
The wavelength changes but not the frequency
Practical
How to investigate refraction
Independent variable- Angle of incidence
Dependent variable-Angle of refraction
Control- Glass block, light source
Place light within ray box that has one slit allowing light to pass through. Then place glass block and outline it on paper in front of ray box. Draw where the light source comes in and leaves the block and draw normal. Then remove block and draw the angle of incidence and angle of refraction. Then meausere angle then repeat with different angles
Reflection is same
2 Uses of all EM waves
Radio-Communication/Navigation
Microwaves-Communication/Microwaves
Infrared- Electric heaters/ Infrared cameras
Visible light-Optical fibres/Illumination
Ultraviolet-Disinfection/Foresnics
X rays/Gamma rays- X rays/Chemotherapy
Explain each
2 types of lenses
Concave- Lens cave inwards. It causes parallel rays of light to spread out. Its principal focus is before the rays hit the lens
Convex- Bulges outwards and causes rays of lights parallel to the axis to be brought together at the principal focus.
3 rules of refraction in convex lens
Incindent ray parralell to lens passes through principal focus on other side
The incident ray also travels parralell to the axis
An incident ray passing through the centre of the lens carries on in the same direction
3 rules of refraction in a concave lens
An incident ray parralell to the axis that travels in line with the principal focus
Passing through the lens towards the principal focus refracts through the lens and parallel to the axis
Incident ray passing through the same direction passes through the centre.
DIfference between virtual and real image
A real image is when light comes from an object together to form an image.
A virtual image is when rays of light appear to be coming from a different place.
3 things to describe an image properly
How big it is
Upright/inverted
Real/Virtual
What image do concave lens create
Always Virtual images
