P12 - Wave Properties Flashcards
What is the nature of waves / what are they?
Waves transfer energy without transferring matter.
*can also transfer information (e.g radio, mobile phone…)
What do all waves involve?
Oscillations/vibrations of some sort.
What pieces of equipment can be used to investigate the properties of waves?
E.g wavespeed, distances etc…
1) Ripple Tank
2) String
3) A solid object
4) A loudspeaker
5) Slinky
Etc…
What 2 categories do waves fall into?
1) Mechanical Waves
2) Electromagnetic Waves
What are Mechanical Waves?
Mechanical waves are oscillations (vibrations) that travel through a medium.
E.g sound waves, water waves, seismic waves from earthquakes etc…
What are Electromagnetic Waves?
Electromagnetic waves are waves that can travel through a vacuum at the speed of light (300,000,000m/s)
No medium is needed.
E.g light waves, radiowaves, microwaves etc…
How do mechanical waves travel?
Either:
Transverse
Longitudinal
How do electromagnetic waves travel?
ONLY Transverse
What is the top of the wave called?
The peak or crest.
What is the bottom of the wave called?
Trough
What is amplitude?
The maximum displacement of a point on the wave from the mean position.
Visually: the distance between the equillibrium line to the top OR bottom of a wave.
How does amplitude impact the amount of energy a wave can carry?
The bigger the amplitude, the more energy the wave carries.
What is wavelength?
Wavelength is the length of one complete wave.
Visually: the distance between one point on the wave, to the equivalent point of the adjacent wave.
Symbol of Wavelength: λ (lambda)
What is Frequency?
The number of waves passing a fixed point per second (or number of oscillations per second).
Unit: Hertz (Hz) e.g 10Hz = 10 oscillations per second.
What is the relationship between frequency and wavelength?
The higher the frequency, the shorter the wavelength.
What is the period of a wave?
The period of a wave is the time taken for each wave to pass a fixed point.
How do you calculate the period of a wave?
period, T (seconds) = 1 / frequency, f (Hz)
IMPORTANT: This is for 1 wave. If it’s any other number, you use that number.
E.g average period of ten waves = 10 / frequency
What wave property affects the pitch of a sound wave, and the colour of a light wave?
Frequency
*Think Football Pitch - ‘F’ for frequency, ‘P’ for pitch.
What wave property affects the volume of a sound wave, and the brightness of a light wave?
Amplitude
*Whence the phrase, turn the volume up. Means increase the amplitude.
What is wavespeed?
Wavespeed is the distance travelled by a wave in a given time.
What is the equation for wavespeed?
Wavespeed = frequency x wavelength
V = f x λ
(m/s) = (Hz) x (m)
*You can also just use speed = distance/time - make sure to always give equipment for the variables (e.g stopwatch for time, metre rule for distance).
How do waves travel?
1) Transverse
2) Longitudinal
What are Transverse Waves?
Waves where the oscillations of particles are perpendicular to the direction of energy transfer.
- vibrations are going up and down
- but the energy is being transferred from left or right
- vibrations are PERPENDICULAR to the direction of energy transfer
Visually: It’s like the worm dance move.
Example:
-All electromagnetic waves travel as transverse waves. E.g light, seismic s-waves…
What are Longitudinal Waves?
Waves where the oscillations of the particles are parallel to the direction of energy transfer.
- the oscillations are going from left to right
- the energy transfer is also going from left to right
- vibrations are PARALLEL to the direction of energy transfer
- there are ‘compressions’ and ‘rarefactions’
Visually: It’s like a slinky.
Example:
- Soundwaves are longitudinal waves.
- Seismic p-waves are longitudinal waves.
What is reflection?
The bouncing of light off a polished surface (mirror), that laterally inverts an object.