P5.1 - Wave Behaviour Flashcards
spec approved
What is a wave?
an oscillation that transfers energy (without transferring matter)
how are sound waves produced?
when vibrations in your vocal cords produce sound waves
How do phones communicate ?
Using Electromagnetic waves
define amplitude
the maximum displacement of a point of a wave from its rest position
Define Wavelength
distance from one peak (or trough) to the next peak (or trough) in m
define time period
the time for one wave to pass a given point or the time for one complete oscillation in seconds (s)
define frequency
the number of peaks passing a point per second (measured in Hz)
What is a rarefaction?
A part of a longitudinal sound wave which has low pressure (wide bits - particles spread far apart)
what is a compression?
a part of a longitudinal wave where the pressure is high
close together lines - because particles are squashed together
state two examples of mechanical waves
sound waves, water waves
A mechanical wave is a wave that is an oscillation of matter, and therefore transfers energy through a medium.
what is a mechanical wave?
a wave that needs medium or matter to travel through
do electromagnetic waves require medium/matter to travel through?
no they do not, can travel through vacuum
state an example of longitudinal waves
sound waves
describe the way transverse waves trave;l
- direction of vibration is at right angles to the direction of travel of the wave
how are transverse waves represented on a spring?
move up and down
how are longitudinal waves represented on a spring?
pushed forward
- springs close together = compressions
- springs far apart = rarefactions
describe one way to model waves
- ripples on water
TRANSVERSE WAVE
(surface of water moves up and down, waves travel, water does not) - showed by cork
does air move when sound waves move?
no - sound is transferred through vibrating molecules, which stay where they are and vibrate about a fixed point
what does a time trace diagram do?
- shows how displacement varies with time
- let us to measure the time period from any point on a wave to point in next
what is the equation to find out the time period?
1
———
frequency
what is the x-axis label on a snapshot diagram?
distance travelled
what is the x-axis label on a time trace diagram?
time (in seconds)
how are waves typically modelled?
using a ripple tank
how do you measure the speed of both kinds of waves?
use a ripple tank
- know the frequency of ripples (by finding number of rotations of motor per second)
- know wavelength (by using a flashing light + ruler)
s = f x w
explain why frequency is not ‘shown’ on diagrams
- Frequency is the number of waves per second
- you cannot show on a diagram.
what is the equation to measure wave speed?
Wavelength (m) x Frequency (hz)
difference between transverse and longitudinal waves (vibration of particles in terms of direction of travel)
o transverse = vibrations at right angles of direction of travel
o longitudinal = vibrations at same direction to direction of travel
considering what kind of wave light travels as, is it a mechanical wave?
light travels as an electromagnetic wave
- so no, it is not a mechanical wave as it can travel without a medium (CAN TRAVEL IN A VACUUM)
why can waves pass through faster in a solid compared to a gas?
as particles are very close together, so vibrations can be passed on very fast (faster wave speed)
how is the amplitude related to the amount of energy a wave carries?
bigger amplitude = more energy the wave carries
how are frequency and wavelength connected?
bigger wavelength = smaller frequency
what is the equivilant to peaks and troughs in a longitudinal wave?
compressions (peaks)
rarefractions (troughs)
what does the velocity of a wave depend on?
the medium that it is traveling through
how are ripples on water surfaces used to model transverse waves
as if cork placed on the surface, it is not carried by the wave (only moves up and down)
how can the speed of a transverse wave be measured using a ripple tank
1) light shone through tank
2) dark + light patches appear underneath it as light passes through crests + troughs
3) count number of times a dark patch passes through a point in a minute, divide by 60 = frequency
4) measure wavelength by the distance between each dark patch between waves
5) then use v = f x w to calculate speed
