P5 Flashcards
What are the two types of waves?
Transverse and Longitudinal waves
What is an example of transverse waves?
ripples on the surface of water
What is an example of longitudinal waves?
sound waves travelling in the air
What do all waves do?
transfer energy from one place to another
What type of energy do ripples in the water transfer?
Kinetic energy
what type of energy do sound waves transfer?
sound energy
What is transverse wave?
a wave that is moving up and down in a moment called oscillation. These movements are perpendicular to the direction of energy transfer
What is a longitudinal wave?
Particles moving from side to side. the oscillations are parallel to the direction of energy transfer
compressions?
regions in longitudinal waves where the air particles are very close together
rarefactions?
regions in longitudinal waves where the particles are spaced out
What do all longitudinal waves require to travel in?
a medium such as air, liquid or a solid
What part of the ripples on a water surface travels??
it is the wave that travels and not the water or air
e.g. shaking a slinky
Amplitude?
the maximum displacement of a point on a wave away from its undisturbed position (middle)
(half of the wave)
Wavelength?
the distance from a point on one wave to the equivalent point on the adjacent wave
(e.g. top of both waves)
how to measure the wavelength on a longitudinal wave?
from one compression to the next compression
or from one rarefaction to the next rarefaction
Frequency?
the number of waves passing a point each second (Hz)
period?
time in seconds for one wave to pass a point
Wave speed?
speed at which the wave moves through the medium (speed at which energy is transferred
wave speed=?
frequency (hz) x wavelength (m)
a method to calculate the speed of sound waves in air?
2 people stand 500m apart
person A holds a pair of cymbals and person B holds a timer. person B starts timing when they see person A hit the cymbals together and stops it when they hear it. The calculate the speed of sound waves by dividing the distance travelled by the time taken
2 problems of the method to calculate the speed of sound waves?
every person has a different reaction time
the time between the symbols clashing and hearing the sound is very short.
what type of waves are electromagnetic waves?
transverse
List of colours on the spectrum from lowest frequency and longer wavelength, to higher frequency and shorter wavelength
1) Red
2) Orange
3) Yellow
4) Green
5) Blue
6) Indigo
7) Violet
What type of wave has the lowest frequency and lowest wavelength?
Radio waves
What type of wave has the highest frequency and shortest wavelength?
Gamma rays
What speed do all electromagnetic waves travel at?
3 X 108 m/s
What causes light to appear to change direction as it passes through the water?
refraction
What causes refraction (glass of water)?
waves can change direction when they change speed (velocity) moving from one medium to another
Wave front?
an imaginary line that connects all the same points in a set of waves
e.g. the water surface in a glass
What happens to the wavefront when it enters a glass of water?
it slows down and the lines become closer together
What happens when we heat atoms?
we cause electrons to move from one energy level to another higher one, so when it returns to its original level, it generates an electromagnetic wave
What 3 types of waves are very hazardous to the body?
Ultraviolet waves
X-rays
Gamma rays
What risks do ultraviolet waves cause to humans?
skin cancer
skin to age prematurely
What do x-rays and gamma rays do when they are absorbed?
they knock electron atoms off, leading to mutation of genes and risk of cancer
What is the dose of radiation measure in?
sieverts(Sv) or millisieverts (mSv)
