Topic 2: Waves and the Electromagnetic Spectrum Flashcards
Complete this sentence .
Waves transfer ______ and ______ but do not transfer _______.
Waves transfer energy and information
but do not transfer matter.
What are the two types of waves?
- Transverse
2. Longitudinal
What is a transverse wave?
A wave for which the oscillations are
perpendicular to the direction of energy
transfer.
What is a longitudinal wave?
A wave for which the oscillations are
parallel to the direction of energy
transfer.
Give two examples of transverse waves.
- Electromagnetic waves
2. Seismic s-waves
Give two examples of longitudinal
waves.
- Sound waves
2. Seismic p-waves
What are the two parts of a longitudinal
wave called?
Compressions and rarefactions.
What are the two parts of a transverse
wave called?
Peaks and troughs.
What is a wave’s amplitude?
The maximum displacement of a point
on a wave from its undisturbed position.
What is wavelength?
● The distance from a point on a wave to
the same position on the adjacent wave
● Most commonly peak to peak or
trough to trough
What is the frequency of a wave?
The number of waves that pass a given point each second.
What is the unit used for frequency?
Hertz, Hz
What is meant by a frequency of 200Hz?
200 waves pass a given point each second.
What is wave speed?
The speed at which energy is transferred through a medium.
What does a wave transfer?
Energy.
What is wave velocity?
Wave velocity (measured in metres per second) is equal to the product of the wavelength and frequency of the wave.
State the equation used to calculate
wave speed. Give appropriate units.
Wave Speed = Frequency x Wavelength
Speed (m/s), Frequency (Hz), Wavelength (m)
What is meant by the period of the wave?
The length of time it takes for one full wave to pass through a point.
What word is used to describe when a wave bounces off a surface?
Reflection.
What is the normal (in terms of reflection and refraction)?
A vertical imaginary line which is
perpendicular to the boundary.
What occurs when light is reflected off a boundary?
It bounces off a smooth flat surface so
that the angle of incidence (the angle it
comes in at) is the same as the angle of
reflection (the angle it leaves at).
What is refraction?
Refraction is the change in speed of a wave as it reaches a boundary between two media, usually resulting in a change in direction (if it enters at an angle).
What occurs when light is refracted at a
boundary?
● The light changes speed and direction in the new
medium
● If the new medium is more dense, the light will
travel slower and bend towards the normal
● If the new medium is less dense, the light will
travel faster and bend away from the normal
When entering a denser material, light
waves…
…slow down and bend towards the
normal.
When entering a less dense material,
light waves…
…speed up and bend away from the
normal.
How can refraction be measured?
The angle of incidence, i, and angle of
refraction, r, can be measured and
compared. All angles are measured
relative to the normal.
What are the effects of absorption of
different wavelengths of waves in
different mediums?
● Some materials behave differently
depending on the wavelength
● An example is glass which will transmit visible light, but reflect UV light
How do sound waves travel through a
solid?
The particles in the solid vibrate and
transfer kinetic energy through the
material.
How do sound waves travel through a solid?
The particles in the solid vibrate and
transfer kinetic energy through the
material.
How does the human ear work?
- The outer ear collects the sound which travels into the ear
- The sound waves cause the eardrum to vibrate at the same
frequency - This is amplified by three ossicles (small bones)
- This causes the hair in the cochlea to vibrate
- The cochlea converts the vibrations into electrical signals
- The signals are passed to brain through the auditory nerve
- The brain converts the electrical signals into sound
What is the frequency range of human hearing?
20 Hz - 20kHz
1kHz = 1000 Hz
What is an ultrasound wave?
A sound wave with a frequency greater
than 20,000 Hz.
What is sound of frequencies less than
20Hz called?
Infrasound.
What natural event causes seismic
waves to be produced? What types are
produced?
● Earthquakes
● They produce both P-waves and
S-waves
Are P waves transverse or longitudinal?
Longitudinal
Are S waves transverse or longitudinal?
Longitudinal