14. P12 P13 Waves and EM Waves (Trilogy) Flashcards
What is the law of reflection?
Angle of incidence(i) = Angle of reflection(r)
What is a transverse wave?
The particle oscillations are perpendicular to the direction of the energy.
Give examples of transverse waves.
light, water, radio, microwave, infrared, UV, X-rays, Gamma
What is a longitudinal wave?
The particle oscillations are parallel to the direction of the energy.
Give an example of a longitudinal wave.
Sound
What is a wave?
A wave transfers energy and information from one place to another.
Define Wavelength
The Wavelength is the length of one complete wave. (the distance between two corresponding points on a wave)
Units of wavelength?
Metres (although can be measured in mm, cm or km)
Define Amplitude
The amplitude is the maximum disturbance caused by a wave from its rest position. (centre line of wave up to the peak or down to the trough)
Define frequency
The frequency is the number of waves passing a point every second.
Units of frequency?
Hertz (or Hz - must be capital H)
Define period (T)
The period is the time it takes for one complete wave to pass a point
Units of time period (T) of a wave?
seconds, s
Equation to calculate wave speed?
wavespeed = frequency x wavelength (v = f x ?) (? - lambda = wavelength)
Equation to calculate time period of a wave from the frequency?
T = 1 / f
In a longitudinal wave, the name given to areas where the particles are close together?
Compression
In a longitudinal wave, the name given to areas where the particles are spread out?
Rarefaction
What is refraction of waves?
The change in the direction of travel when a wave crosses a boundary between one medium to another due to the wave changing speed.
Water waves refract when what causes the speed of the wave to change?
Depth of the water
Light waves refract when what causes the speed of the wave to change?
Moves from one material to another of a different optical density.
The line on a ray diagram that all angles are measured from during reflection or refraction?
normal
How do you draw a normal line at the point the light strikes the mirror?
Normal line is drawn perpendicular to the surface at the point the ray strikes the surface (using a dashed line)
What is the speed of sound waves in air?
330m/s although it does vary with temperature.
How does a sound change when the amplitude decreases?
Quieter
How does a sound change when the Wavelength increases?
Lower pitch
How does a sound change when the frequency increases?
Higher Pitch
Describe what is meant by a mechanical wave.
A wave that requires a medium in which to travel i.e. water or a spring etc
Describe what is meant by an electromagnetic wave.
Transverse waves that transfer energy by setting up electric and magnetic fields. Can travel through a vacuum.
What is meant by the crest or peak of a wave?
The highest part of a transverse wave
What is meant by the trough of a wave?
The lowest part of a transverse wave
List the Electromagnetic waves in order from long to short wavelength
Radio, Microwave, Infrared, Visible, UV, X-ray and Gamma
List the Electromagnetic waves in order from high to low frequency
Gamma, X-ray, UV, Visible, IR, Microwave, Radio
State how a radiowave can be produced?
Oscillation in electrical circuits (vibration of charged particle such as electron)
State a use of radiowaves?
Communication, television and radio
State two uses of microwaves?
Heat food, mobile phones, Satelite tv, GPS
State two uses of infrared?
heater, toaster, oven, treatment of muscle injuries, remote controls, infrared cameras
State two uses of UV light?
Check for forged bank notes, sunbeds, investigating crime scenes, energy efficient lightbulbs.
State two uses of X-rays?
airport security, check for broken bones
State two uses of Gamma radiation?
Radiotherapy, sterilising surgical equipment, medical tracers, industrial tracers
What are the two similarities of all electromagnetic waves?
All transverse, travel at the same speed in vacuum or air, transfer energy
State the colours which make up visible light?
Red,Orange, Yellow, Green, Blue, Indigo and Violet.
State a danger of UV light?
Ultraviolet waves can cause skin to age prematurely and increase the risk of skin cancer.
State which types of EM waves are ionising radiation?
UV, X-ray and Gamma
State what the effect on human tissue when they absorb Radio, Microwave, IR or visible?
Heating
State what effect ionising radiation can have on human cells?
Can cause the mutation of genes and cancer.
What two things do the effects of ionising radiation have on human body tissue depend on?
1) type of radiation and 2) the size of the dose.
Radiation dose is measured in Sieverts, what is it a measure of?
It is the measure of the risk of harm resulting from an exposure of the body to the radiation.
How many millisieverts are present in 5 sieverts of radiation dose?
5000millisieverts = 5 sieverts
Which type of EM radiation can be used by fibre optic cables?
IR and visible light
How are gamma rays generated?
Gamma rays are generated from changes within the nucleus of atoms.
