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)
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
and pattern
Radio
Microwaves
Infra Red
Visible light
Ultra violet
X rays
Gamma rays
Increasing frequency/Decreasing wavelength
Explain
Refraction
When waves cross boundary between materials at an angle it changes direction and its refracted.
The wavelength changes but not the frequency
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
Primary colours
Red/Green/Blue
When all are mixed it creates white light
Explain an opaque object and what determines its colour
Opaque objects do not transmit light. They absorb some wavelengths of light and reflect the rest.
An object may appear to be red as red is most strongly reflected from the object. The other wavelengths are absorbed.
If an object relfects a colour that isnt primary it must be reflecting both colours or the light colour
Difference between white and black objects
White objects reflect all of the wavelengths of light equally
Black objects absorb all wavelengths of light
What is a primary colour filter
They only let one primary colour shine through the light. If blue light was shone on a red object or something made from not blue light then it would appear black as all light is absorbed
2 facts about infrared radiation
An object hotter than its surrounding emits more IR radiation than it absorbs as it cools down
Objects at a constant temperature emit infrared radiation at the same rate they absorb it.
Explain black body radiation
A perfect black body is an objec tthat absorbs all of the radiation that hits it
Perfect black bodies are the best possible emitters of radiation.
As the temperature of an object increases the intensity of every emitted wavelength increases. The intesnity increases more rapidly for shorter wavelengths.
How do sound waves work
1 fact
Caused by vibrating objects. The vibrations pass through the medium as compressiosns and refractions
Travels faster in solids than liwuids and gases
How do we hear
Sound waves reach ear drum which vibrates
Vibrations transfer to tiny bones in ear then to cochlea
Cochlea transfers vibrations to electrical signals
