Waves Flashcards
(31 cards)
What is wavelength?
The length of a full cycle of a wave
What is amplitude?
The space from the middle line to the trough or crest
What is frequency?
The number of complete waves passing a certain point per second
What are the two types of wave?
Transverse and longitudinal
What are transverse waves?
Waves that have sideways vibrations e.g. electromagnetic waves, ripples on water
l l l
l l l l l
l l l etc
What direction are the waves in transverse waves?
Perpendicular (at 90 degrees) to the direction of energy transfer of the wave
What are longitudinal waves?
Waves that have vibrations along the same line e.g. sound waves, shock waves
l l l l lll l l l l l l lll l l l l l l l llll l l l l l l llll l l l l etc
What direction are the waves in longitudinal waves?
Parallel to the direction of energy transfer of the wave
What are the units in the speed=frequency x wavelength?
m/s, Hz, m
How can waves be affected?
By reflection, refraction and diffraction
What is reflection?
When light bounces off an object and allows us to see it
What allows you to see your reflection in a mirror and not a piece of paper?
The paper has a very uneven surface so the light reflects off at different angles. However, the mirror is very smooth and shiny, so the light just reflects straight off, allowing you to see your reflection
What is the law of reflection?
Angle of incidence = angle of reflection
How do you draw a ray diagram for an image in a plane mirror?
- Draw the virtual image behind the mirror the same size and the same distance from the mirror
- Then draw a ray from the top of the eye to the top of the virtual image (bold in front , dotted behind the mirror)
- Draw the incident ray from where the line touches the mirror to the top of the real object
- Do the same for the bottom ray
What is refraction?
When waves change direction as they go through an object due to them changing speed through different densities
What happens when a wave refracts?
It hits an object and slows down, and if it hits it straight on at the normal, it won’t bend, but if it hits it at an angle, it will bend towards the normal, the bend away from the normal when it comes out
What is diffraction?
When waves pass through a gap and spread out
How does the size of the gap affect diffraction?
When the gap equals the wavelength, there is the maximum diffraction, if the gap is much wider, there is very little diffraction, and if the gap is only a little bit wider, it will slightly diffract
What is the electromagnetic spectrum?
A continuous spectrum of electromagnetic waves
What are the waves in the EM spectrum?
Radio Microwaves Infrared Visable Ultra-violet X-rays Gamma
What are the wavelengths in the EM spectrum?
From about 10(-15)m to 10(4)m
What speed do EM waves travel at?
The speed of light (3 x 10(8) m/s)
What are radiowaves used for?
Communication, because the shorter waves reflect off the ionosphere and the longer waves diffract around the earth
What are microwaves used for?
Satellite communication and mobile phones, as they can pass through the ionosphere to reach satellites, which transmit the signal back to earth, and for heating food as they are the right wavelength to pass through water molecules and heat them up
