Topic 4- Waves Flashcards
What do waves transfer?
- Energy
- Not matter
How do we know matter doesn’t move in sound and light waves?
Light- particles oscillate up and down
Sound- particles vibrate back and forth
- Ducks (toy) don’t move in water
What is frequency?
How many waves per second
What is wavelength?
Length of a full wave, from peak to peak
What is amplitude?
- The height, equilibrium to the peak/trough
- Loudness of a sound wave/ brightness
What is the period?
How many seconds it takes one complete wave to pass a point.
What is the wave velocity?
- Speed of the wave in a given
direction - changes in different mediums
What is a wavefront?
- Lines that show the peak of a wave that vibrate in unison.
- Equal distance from eachother
What is a longitude wave?
- A wave with areas of compression and rarefaction
- Oscillations occur parallel to the energy movement
- sound waves
What is a transverse wave?
- Wave with a peak and trough
- Oscillations occur perpendicular to the energy movement
- Light/electromagnetic waves
What are two examples of longitudinal waves?
- Sound
- P seismic
What are three examples of transverse waves?
- Electromagnetic (light)
- S seismic
- Water
What are properties of P seismic waves ?
- Can travel through solids and liquid
- Produced by earthquakes
- Faster than S seismic
What are properties of S seismic waves ?
- Slower than P seismic
- Only travel through solids
- More destructive
How do we calculate wave speed?
Wave speed= frequency x wavelength
v=fxλ
Describe how to measure the velocity of sound in air with humans + what are the issues?
1) Place two people across a measured distance (e.g 100m)
2) Person A makes a visual and noise making gesture (e.g loud clap)
3) Person B beings top watch when sees and ends when hears
4) Repeat
5) Human reaction times differ for sound + light
Describe how to measure the velocity of sound in air in microphones?
1)Place 2 microphones 1 metre apart
2)attach to a computerised ossciloscope
3)Make a loud bang at microphone 1
4)M-1 and M-2 will pick up sounds at different times
Describe how to measure the velocity of sound in ripples?
1) Ripple tank
2) Record waves movement
3) Find frequency by calculating how many waves pass a point per second
4) Find wave fronts (shadow) and measure the distance
5) Use wavespeed= wavelength x frequency
Core Practical: Investigate suitibility of equipmenent to find the frequency, speed and wavelength of a wave in a fluid
1) Record a ripple tank (frequency =no. of waves per second)
2) Place ruler udner ripple tank + use shadows to find wavelength
3) Wave speed = wavelength x frequency
Core Practical: Investigate suitibility of equipmenent to find the frequency, speed and wavelength of a wave in a solid
1) Suspend metal rod with a clamp stand and a rubber band
2) Attach data logger and 2 microphones to each end
3) Start data logger (short time so more precise)
4) Hit one end with hammer
5) Micropohones pick up sound and when it eaches the other end (in data logger) -the time
6) Use distance/time= speed
How to calculate depth from time and speed of a wave?
(time/2)x speed
What is transmission
-Wave passes through an object without being absorbed
What is reflection?
-Wave bounces off the boundry between 2 different mediums
-Angle of incidence= Angle of reflection
What is refraction?
1) An wave speeds up/ slows down when entering a materil with a different density
2) To keep the same frequency, its wavelength shorterns (all inter-related)
incidence ray, refracted ray and emergant ray
