P1.5 Waves Flashcards
What are the 2 types of wave?
Transverse or Longitudinal
Describe the oscillations in transverse waves
In transverse waves the oscillations are perpendicular to the direction of energy transfer
Describe the oscillations in longitudinal waves
In longitudinal waves the oscillations are parallel to the direction of energy transfer
What type of waves are electromagnetic waves?
transverse
What type of waves are longitudinal?
sound waves
Give some examples of mechanical waves
water waves, shock waves, waves on a rope
What type of wave are mechanical waves?
transverse or longitudinal
All types of electromagnetic waves travel at the ——– speed through a vacuume.
SAME
What sizes do wavelengths in the electromagnetic spectrum vary from?
about 10 to the -15 to more than 104 meters
What is the order of waves in the electromagnet spectrum, from long wave length to short wave length?
radio waves- Long wave length
microwaves
infrared waves
visible light
ultraviolet
Xrays
Gamma rays
What do longitudinal waves show areas of?
Compression and rarefaction
When do you see a clear reflection in the mirror?
When light travelling in the same direction reflects from an even surface so it is all reflected at the same angle
What is the law of reflection?
Angle of incidence = Angle of reflection
What is the normal?
A construction line perpendicular to the reflecting surface at the point of incidence
What is diffraction?
When waves bend round obstacles causing the waves to spread out.
What does the amount of detraction depend on?
the size of the gap relative to the wavelength of the wave
When does significant diffraction only occur?
When the wavelength of the wave is of the same order of magnitude (same size) as the size of the gap or obstacle.
Why is light hard to diffract?
As it has a vey small wavelength so needs a very small gap.
What is refraction?
When waves go through a new material, causing them to change direction
In refraction, when are waves not refracted ?
if waves travel along the normal.
To be refracted they need to meet the medium at an angle
What is the amplitude of a wave?
the displacement from the rest position to the crest.
What is the wavelength of a wave
The length of the full cycle of the wave
eg- from crest to crest
What is the frequency of a wave?
The number of complete waves passing a point per second
OR
The number of waves produced by a source each second
What do waves transfer?
energy
in the equation: speed= frequency x wavelength (v= f x y)
What are the units?
v , speed- m/s
f , frequency- Hz
y, wavelength- m
Describe the uses of radio waves
COMMUNICATION
- Long wave length means the wave diffracts around the curved surface of the earth and around hills and into tunnels.
- Used for TV and FM radio
Describe the uses of microwaves
SATELLITE COMMUNICATION and MOBILE PHONES
-Pass easily through atmosphere
What are some possible risks with mobile phones?
mobile uses microwaves to pick up signals.
Some wavelengths in microwaves are absorbed by water molecules and heat them up. If the water happens to be in your cells, they may become damaged.