P12- Wave Properties Flashcards
Wave
A wave is a means of transferring energy from one place to another without a transfer of matter between the two points.
Types of waves
Mechanical waves, EM (Electronagnetic) waves
Mechanical waves
Vibrations that travel through a medium
Examples of mechanical waves
Sound waves, water waves, waves on springs and ropes, seismic waves
Electromagnetic waves
Waves that can travel through a vacuum at the speed of 300,000,000 m/s. No medium is needed.
Examples of EM waves
Light waves, radio waves and microwaves
Transverse waves
The direction of oscillation is perpendicular to the direction of motion of the wave.
What type of wave are all EM waves?
Transverse waves
Longitudinal waves
The direction of oscillation is parallel to the direction of motion of the wave.
What type of wave is a mechanical wave?
It can be transverse or Longitudinal
Wave speed (ms^ -1) Equation
Frequency (Hz) x Wavelength (m)
Amplitude
Distance from the rest position to the top of the wave.
Frequency
The number of waves or oscillations per second (Hz).
Time period
The tine for one wave to pass a given point or the time for one complete oscillation (s).
Wavelength
Distance from one point on the wave to the identical point on the next wave.(m).
Every second, 8 waves pass through the gap in the barrier. The waves have a wavelength
of 0.015 metres.
Calculate the speed of the water waves and give the unit.
8/1 = 8Hz
8 x 0.015 = 0.12m/s
The Law of reflection
The reflected waves move away from the barrier at an equal angle to the incident waves.
Angle of incidence = angle of relection
What can we use to investigate waves?
A ripple tank
How does a ripple tank work?
Ripple tanks allow us to produce waves and observe how they behave when we introduce barriers, different gaps and change how deep the water is.
Refraction
Refraction occurs when a wave changes direction as it changes speed when it passes from one medium to another. So the wavelength change as well but the frequency remain unchanged.
What happens if a wave slows down?
It refracts toward the normal
What happens if a wave speeds up?
If refracts away from the normal
Transmission
The wave passes from the first material into the second material.
Absorption
the energy of the wave will be transferred to the energy store of the second material.
The audible range for human hearing is between …
20 Hz and 20,000 Hz
What frequency are ultrasound waves?
Over 20,000 Hz
What is an ultrasound scanner?
It is an electronic device which makes use of a ‘transducer’ which can be placed on a surface through which it can sendpulses of ultrasound waves which can then also be detected – the results can then be shown on a display screen.
Why can’t X rays be used for baby scans?
Because they pass through organ tissue and because they are ionising(potentially harmful).
Equation for finding distance with sound
Distance (m) = 1/2 x speed of ultrasound wave (m/s) x time (s)
What is the problem with X-rays passing through organ tissue?
Unable to see defects in organ tissue
What is an echo?
The reflection of a soundwave from a surface
What is the study of Earthquakes called?
Seismology
What are P-Waves?
The P stands for primary. These are push pull waves which are longitudinal.
Key features of P-Waves?
● They can travel through liquid and solid so they can travel through the
earth’s core.
● They travel fast.
● They are bent by the changing density of the rock.
● They are bent sharply when the material changes suddenly.
What are S- Waves?
S stands for secondary waves. They are side to side waves (transverse).
Key features of S-Waves
● They can only travel through solids.
● They are slower than P-waves.
● They are bent by the changing density of the rock.
● They are bent sharply when the material changes suddenly.
What are L waves?
L-waves (Long waves), arrive last and cause violent movements on
the surface up and down as well as backwards and forwards. They
travel more slowly than P-waves or S-waves, and they only happen in
the Earth’s crust.
