Waves Done

Question	Answer
Longitudinal Waves	A wave that vibrates in the direction of energy release.E.g Sound Waves
Transverse Waves	A wave that the Vibration is at a right angle to the direction.
What is Frequency	How many waves are in a certain time period (usually 1 second)
What is Amphlitude	how big the wave is (determines the volume of the sound)
What is a Wavelength	is the length of a full wave from one point of the wave to the same point of the following wave.
Wave Speed =	Frequency x Wavelength f x λ
How Frequency relates with time period	Image: Tim2 (binary/octet-stream)
The Colours in Visible Light	Red Orange Green Yellow Blue Indigo Violet
Electromagnetic Colour Rule	All electromagnetic waves travel at the same speed in free space. The higher the frequency, the higher energy
Electromagnetic Spectrum	Radio waves Microwaves Infra-Red Radiation Visible Light Ultra Violet X Rays Gamma Rays
Radio Waves Uses	Broadcasting and communications
Microwaves Uses and Dangers	Cooking and satellite transmissions Internal heating of body tissue
Infra-Red Radiation Uses and Dangers	Heaters and night vision equipment Skin burns
Ultra Violet Uses and Dangers	Fluorescent lamps Damage to surface cells and blindness
X- Rays uses	Observing the internal structure of objects and materials and medical applications
Gamma Rays Uses and Dangers	Sterilising food and medical equipment Cancer, mutation
Wavefronts	A wavefront is an imaginary surface representing corresponding points of a wave that vibrate in unison. When viewed from above it can be seen as like a peak of the wave
The Doppler Effect	As the ambulance travels towards you the emitting of the sound stays constant. However since it’s moving towards you and its travelling slightly closer to the speed of sound it emits the sound closer to the previous sound wave. This means when that there is a higher frequency which therefore means a higher pitch. When the ambulance passes you the frequency decreases along with the pitch because the ambulance is travelling away from you so the wavelengths increase. This is because the sound source is moving away from you meaning the ambulance emits the sound wave further from the last.
Reflection	- Know that Light Waves are Transverse and Sound Waves are Longitudinal but both can be reflected and refracted. Light moves in STRAIGHT LINES that’s why we can’t see around the corner. - Sound waves produce echoes which are reflections of waves. This also tells us that sound travels slower than light as echoes take a significant time to reach us. - The angle of incidence is equal to the angle of reflection, - I = r
Refraction	Refraction is when a wave hits a denser object causing it to decrease in speed and change direction. However it depends on the angle of incidence. When it hits the block the density increases making the speed decrease along with the wavelength. The light always bends towards the normal. The number of how optically dense an object is the refractive index. It is a number that tells us how much light slows down (compared to light travelling through a vacuum).If the refractive index was 2, it would mean that light travels 2 times faster in a vacuum. Refractive index = sin i / sin r
The Critical Angle	- The critical angle is the last angle that refraction happens at which light is refracted at 90 degrees along the surface edge. c= sin^-1 (1/n) - Diamond has a very large refractive index, meaning light will reflect more often- this is what causes it to sparkle.
Total Internal Reflection	- It can only happen when it goes from a higher reflective index to a lower reflective index. - Only happen if angle > than the critical angle. An example is fibre optic cables.
Hearing Sound	- Longitudinal Sound Waves are travelling through the air as vibrations of air molecules and those vibrations are being detected by your ears. Range of Human hearing is 20 - 20,000 Hz Infrasound is below 20Hz Ultrasound is above 20,000Hz Speed of sound is 330m/s
Seeing Sound	The X axis on the oscillation machine shows the time period, one box = 1 time period. The Y axis shows the voltage reading which shows the sound. The sound gets displayed by sound being converted into voltage and displayed then on the screen. If we change the divisions the wave will look different on the screen however will be the same value.

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	Created by Maxime PANS almost 8 years ago