P5 - Waves in matter Flashcards
How is energy transferred by a wave?
Energy is transferred in direction wave is travelling without any transferring matter (particles stay in the same spot)
What is the amplitude?
The distance from the crest to the resting position.
What is the wavelength?
The lengths of one complete wave (eg from crest to crest)
What is the frequency?
The number of complete waves that pass a point in one second (Hz)
What is the period?
The number of seconds it takes for one complete wave to pass.
Equation for period?
Period = 1 / Frequency
What is a transverse wave?
The particles / oscillations vibrate perpendicular to the wave direction.
Examples of transverse waves?
1) All electromagnetic waves
2) Waves in water
3) Light (an electromagnetic wave)
4) S waves
Transverse waves and liquids:
These waves can travel on surface of a liquid but not through it.
What are longitudinal waves?
The particles / oscillations vibrate parallel to the direction of the wave direction.
Example of longitudinal waves?
1) Sound waves
2) P waves
Wave speed equation:
Wavespeed (m/s) = wavelength (m) x frequency (Hz)
or
Speed (m/s) = distance (m) / time (s)
How do you convert Kilohertz (KHz) and Megahertz (MHz) into Hertz (Hz)?
1 KHz = 1,000Hz (Multiply by 1,000)
1 MHz = 1,000,000 Hz (Multiply by 1,000,000)
Experiment to find speed of sound?
Do the OSCILLOSCOPE method:
1) Connect two microphones to a oscilloscope which will display the sound waves
2) Move one microphone away so that the waves on the oscilloscope are the same, but have moved one wavelength apart.
3) Measure the distance between the microphones (finding the wavelength)
4) Find frequency (whatever the signal generator was set to)
5) Use the wave speed =wavelength x frequency equation
Experiment to find the frequency?
- You will need a cork and stopwatch
1) Float cork in ripple tank and it should bob as wave passes
2) When cork is a top of bob start stopwatch
3) Count how many bobs in a set time
4) Divide by number of seconds timed to find bobs per second which is the waves per second (Frequency)
Experiment for wavelength?
- Record or take picture of waves from birds eye view in ripple tank.
- Measure the distance of multiple waves (eg 10) and divide by number of waves to find average wavelength (if 10 waves was 26 cm then 1 wave will have wavelength of 2.6 cm)
Experiment for measuring wave speed?
- Use large piece of paper, pencil and stopwatch
1) Place large piece of paper in front of ripple tank
2) As wave moves across tank, one person tracks the wave’s crest with pencil and straight line on the large piece of paper.
3) The second person should use stopwatch and time for a certain amount of time. When time is finished the first person should stop drawing.
4) Use equation speed = distance / time - Distance for line measurement
- Speed for the time on stopwatch
What 3 things can happen when a wave hits a boundary?
Absorbed: it transfers energy to the second material’s energy stores
Transmitted: It goes through material (often at different velocity’s which lead to refraction).
Reflected: it can bounce of the second material and sent back.
What is the one simple rule for reflection?
Angle at incidence = angle at reflection
What does the reflection of visible light let us do?
It lets us see colour as the light bounces of objects into out eyes.
What is clear reflection?
When light reflects of smooth surfaces (eg mirror) all in the same direction.
What is White light?
It is made of all the colours of light which have different wavelengths.
What happens to the colours of light when white light is reflected?
When white light is reflected, colours of light reflect as same angle and DON’T split as they follow reflection rule (angle at incidence = angle at reflection).
What is refraction?
When a wave bends