P12 Flashcards
WHAT IS A WAVES JOB?
Transfer energy from one place to another
WHAT DO WAVES NOT TRANSFER?
matter
WHAT IS THE RELATIONSHIP BETWEEN WAVE DIRECTION AND ENERGY TRANSFER?
Direction wave travels is the same direction energy is transferred
HOW DO WAVES MOVE?
Oscillation of particles
WHAT DIRECTION ARE TRANSVERSE WAVES OSCILLATIONS?
Up and down they are perpendicular to waves energy transfer
WHAT DIRECTION ARE LONGITUDIAL WAVES OSCILLATIONS?
Left to right they are parallel to waves energy transfer
GIVE AN EXAMPLE OF A TRANSVERSE WAVE?
A water wave or electromagnetic waves
GIVE AN EXAMPLE OF A LONGITUDIAL WAVE?
A spring contacting and relaxing
MECHANICAL WAVES CAN…
Travel through a medium
they can be transverse and longitudial
ELECTROMAGNETCI WAVES CAN…
Travel through a vacuum they are only transverse
GIVE AN EXAMPLE ELECTROMAGNETIC WAVES?
Light wave or Radio wave
WHAT IS AMPLITUIDE?
Height of wave crest or depth of wave trough from midpoint of wave
WHAT IS WAVELENGTH?
distance of wave from crest to crest or trough to trough
THE GREATER THE AMPLITUIDE OF THE WAVE?
the more energy it is transferring
WHAT IS FREQUENCY?
Frequency is the number of waves that pass a point in 1 second
WHAT IS FREQUENCY MEASURED IN?
Hz
WHAT IS THE EQUATION FOR FREQUENCY?
f =1/Time
WHAT IS THE PERIOD OF A WAVE?
Time taken for one wavelength to pass a point
WHAT IS THE EQUATION FOR PERIOD OF WAVE?
Period of wave=1/ Frequency
WHAT IS EQUATION FOR WAVESPEED?
wavespeed= frequency x wavelength
v (m/s)= f (Hz) x Wavelength (m)
WHEN A WAVE MEETS A BOUNDARY WHAT THREE THINGS CAN HAPPEN?
-Absorbtion
- Transmittion
- Reflelection
WHAT IS ABSORBTION?
When energy is transferred directly from wave to material
WHAT IS TRANSMITTION?
When wave passes through a medium
WHAT IS REFLECTION?
When wave does not enter material at all
WHEN DOES REFLECTION OCCUR?
When there is no change in wavespeed or length
ON A REFLECTION RAY DIAGRAM WHERE IS THE NORMAL?
perpendicular and 90 degrees from the boundary
WHAT IS THE RULE FOR ANGLES ON A REFLECTION RAY DIAGRAM?
Angle of incidence= Angle of reflection
WHEN DOES SPECULAR REFLECTION OCCUR?
When normal are all in same direction and 90 degrees from boundary
GIVE AN EXAMPLE OF A SURFACE WHERE SPECULAR REFLECTION WOULD OCCUR?
A mirror
WHEN DOES SCATTERED REFLECTION HAPPEN?
When surface is rough so direction of normals is irregular
EXPLAIN WHY REFRACTION HAPPENS?
Because waves change speed and wavelength when they cross a boundary of two different mediums, if the wave does not meet the medium at directly 90 degrees refraction occurs.
WHY DO WAVES TRAVEL AT DIFFERENT SPEEDS IN DIFFERENT MEDIUMS?
BECAUSE DIFFERENT MEDIUMS HAVE DIFFERENT DENISITIES
THE HIGHER THE DENISITY OF AN OBJECT?
The slower the wave moves through it
IF A MEDIUM IS MORE DENSE THE RAY WILL…
Bend towards the normal
WHAT ARE WAVES THAT CARRY ANY KIND OF SIGNAL CALLED?
Carrier waves
WHAT TWO WAVES ARE USED FOR COMMUNICATIONS ?
Radiowaves and microwaves
WHEN IT COMES TO COMMUNICATIONS THE SHORTER THE WAVELENGTH..
the more information that can be carried bu can only travel a shorter range
WHAT ARE OPTICAL FIBRES AND HOW DO THEY WORK?
Optical fibres are tubes are glass that carry visible light waves through specular reflection. visible light waves have shorter wavelength so can carry more information
WHY ARE MICROWAVES USED FOR SATELLITE AND PHONE?
because they can travel through atmposphere
