Waves Flashcards
What is wavelength?
Wavelength is the distance from a point on one wave to the equivalent point on the adjacent wave.
How is wavelength measured and what is the symbol for it?
Wavelength is measured in metres, and the symbol for it is the greek letter lambda, λ
What is amplitude?
Amplitude is the maximum displacement of a point on a wave from its undisturbed position.
What is frequency?
Frequency (f) is the number of complete waves passing a point in one second.
How is frequency measured?
Frequency is measured in hertz (Hz), frequencies can also be given in kHz and MHz.
What are the values of kHz and MHz?
1000Hz = 1kHz
1000kHz = 1 MHz
What is the time period?
The time period (T) is the time to complete one wavelength. It is the inverse of frequency.
How do you find the time period? (the equation)
T = 1/f
How do you find frequency from the time period? (the equation)
f = 1/T
What is the wave equation?
wave speed = frequency x wavelength
v = f λ
What is wave speed?
The wave speed is the speed that the wave moves at.
What are the units for wave speed?
m/s
What is a transverse wave?
A transverse wave is a wave where the particles move perpendicular to the direction the wave travels.
What is a longitudinal wave?
A longitudinal wave is a wave where the particles move parallel to the direction the wave travels.
What is a compression?
A region in a longitudinal wave where the particles are closest together.
What is a rarefaction?
A region in a longitudinal wave where the particles are furthest apart.
How do the vibrations work in a transverse wave?
The vibrations move from side to side at a right angle to the direction of energy transfer.
How to the vibrations work in a longitudinal wave?
The vibrations move parallel to the direction of energy transfer.
What type of wave is a water wave?
A water wave is a transverse wave.
What type of wave is a sound wave?
A sound wave is a longitudinal wave.
How can you use a cathode ray oscilloscope to show sound waves?
A microphone can be connected to a cathode ray oscilloscope to display sound waves on graphs that make them look like transverse waves.
What is a medium?
A material through which a wave travels.
What do all waves transfer?
Energy
What is the equation for speed?
speed = distance/time
What is the incident ray in a ray diagram?
The incident ray is the ray coming in from the wave source to the surface.
What is the reflected ray in a ray diagram?
The reflected ray is the ray coming away from the surface.
What is the normal?
The normal is a line 90’ to the boundary and is the line from which all angles are measured.
What three things does a wave do when meeting the boundary between two materials?
Refection, absorption, and transmission.
What does it mean if a wave is transmitted?
If a wave is transmitted, it means the wave passes through a material or medium without being fully absorbed or reflected.
What is the angle of incidence?
The angle of incidence is the angle from the incident ray to the normal.
What is the angle of reflection?
The angle of reflection is the only from the reflected ray to the normal.
What is the law of reflection?
The angle of reflection and the angle of incidence are equal.
What is refraction?
Refraction is where a wave changes direction when it enters a different medium.
What do i and r mean in a ray diagram?
i = the angle of incidence
r = the angle of reflection
Why does refraction happen?
If the material the ray enters is denser, the light slows down and bends towards the normal.
What is the angle of refraction?
The angle of refraction is the angle the refracted ray makes with the normal to the refracting surface.
What happens when the light exits the material? (refraction)
When the light exits the material, it speeds up again and the ray refracts again, away from the normal. The angle of refraction is greater than the angle of incidence.
What is a specular reflection?
A specular reflection is a reflection where the surface is very smooth and all the rays are relected at the same angle.
What is a diffuse reflection?
A diffuse reflection is a reflection where the surface is rough and the rays are reflected at many different angles.
How fast does sound travel through solids, liquids, and gases and why?
Sound travels fastest in solids and slowest in gases. This is because the particles are closer in solids than in gases.
Why can we hear?
We can hear because the kinetic energy of the sound wave in air is transferred to the eardrum.
What is the hearing range of a human?
20Hz-20000Hz
What is ultrasound?
Ultrasound is sound waves with a frequency above 20000 Hz. Humans cannot hear ultrasound waves.
What is ultrasound used for?
Ultrasound is used to build up an image of an internal structure that cannot be seen from outside. They are used for scanning unborn babies or to find cracks in metal objects
How do earthquakes happen?
Earthquakes happen when two parts of the earths crust slide past each other suddenly at a fault.
What is a seismic wave?
A seismic wave is a vibration that travels through the Earth, typically caused by earthquakes.
What are the two types of seismic waves?
P and S waves
What is a P wave?
A P wave is a primary (pressure) wave. It is longitudinal wave similar to a sound wave.
What is an S wave?
An S wave is a secondary (shear) wave. It is a transverse wave.
What is the speed of a P wave?
The speed of P waves generally increases with depth in the earth, but it is slower in liquids than in solids.
What is the speed of an S wave?
The speed of an S wave generally increases with depth in the earth, but they cannot travel through liquids.
What is the speed of an S wave compared to a P wave?
S waves are ALWAYS slower than P waves.
Can P and S waves travel through the earths core?
P waves can travel through the earths core ( a liquid), S waves cannot.
What is a seismometer?
A seismometer is a tool used to detect seismic waves from an earthquake.
What are the different rays on the electromagnetic spectrum?
Radio waves, microwaves, infrared, visible, ultraviolet, X-rays, gamma rays
What do all the waves in the electromagnetic spectrum have in common?
All waves in the electromagnetic spectrum are transverse, and transfer energy.
What is the visible spectrum?
The visible spectrum is the different wavelengths of different colours we can see.
What can electromagnetic waves travel through?
Electromagnetic waves do not need a medium to travel through, they can travel through a vacuum.
How are the waves in the electromagnetic spectrum ordered?
By wavelength/frequency. Radio waves have long wavelengths, and gamma rays have short wavelengths.
What does a short wavelength mean in an electromagnetic wave?
A high frequency. The shorter the wavelength, the higher the frequency, and the dangerous the radiation.
What is the speed electromagnetic waves travel in a vacuum?
3 × 10⁸ m/s
