Longitudinal Waves, Sound and Electromagnetic radiation. Flashcards
In a longitudinal wave the disturbance is …….. to the direction (…………) of the wave.
Give a synonym for direction (above)
Parallel
Propagation
Definition of a Longitudinal wave
A longitudinal wave consists of a series of consecutive compressions and rarefactions that move in the direction of propagation.
The particles of the medium move ……… and ………. /The direction of the disturbance moves …………. and ……………
We call these movements …………….. and ……………….
to and fro
Compressions and rarefactions
Compression: The part of the wave where the particles ………………
Rarefactions: The part of the wave where the particles ………………
Compressions: Particles move together (Squished)
Rarefactions: Particles move apart (Stretch)
Is the period, frequency and speed the same as a Transverse wave?
Yes
What kind of wave is a sound wave?
Longitudinal / Pressure wave
What affects the loudness of a sound wave?
Amplitude: Higher Amplitude, Louder sound
What is the only area with no sound?
Vacuum
What pressure does a compression have?
What pressure does a rarefaction have?
Compression: High pressure
Rarefactions: Low pressures
Definition of Oscillation
The vibration of the particles in a medium
Sound can only travel in one direction
True/False
False, it can reflect off hard surfaces
What is an echo?
When we hear a reflected sound wave as a separate sound.
What are the three things that affect the speed of sound?
Temperature: Faster in hot substances, slower in cold substances.
Pressure of the medium
Density: Faster in solids, slower in gasses.
What indicates the pitch in a sound wave?
The frequency: The higher the frequency the higher the pitch
What is the tone in a sound wave?
Measure of the quality of the sound.
Sonar stands for?
Sound Navigation and Ranging
To what range can humans hear frequencies?
Between 20 to 20 000 Hertz!
It decreases as you get older
Waves with a frequency lower than 20 Hz is called …………
Waves with a frequency higher than 20 000 Hz is called ……………
Lower: Infrasound
Higher: Ultrasound
Some uses of Ultrasound…
Detecting objects Measuring distances Imaging in medicine Industrial cleaning and mixing Accelerating chemical processes
In 1873 the Scottish physicist …………….. developed a unified theory of electromagnetics.
What does this theory deal with?
James Clerk Maxwell
This deals with how electrically charged particles interact with each other and magnetic fields.
What are the four main electromagnetic interactions?
1: Attractive and Repulsive forces between electric charges.
2: Magnetic poles (come in pairs that attract and repel each other like electric charges do)
3: An electric current in a wire produces a magnetic field.
4: A moving electric field produces a magnetic field. And vice versa.
What is known as wave particle duality?
The fact that we can use the wave nature or the particle nature of radiation (light) to explain the properties of electromagnetic radiation.
When is electromagnetic radiation created?
When an atomic particle is accelerated by an electric field, causing it to move.
What does the movement of the particles in electromagnetic radiation produce?
The movement produces oscillating electric and magnetic fields. They travel at right angles to each other in a bundle of light energy. (Called a photon)
What two letters of the alphabet could speed be?
v and c
What is the speed of light in a vacuum?
3 x 10^8 m.s^-1
3 times 10 to the power of 8, metres per second
What do dolphins and bats use to navigate?
Echolocation
What are the two things Radiation (Light) can mean?
Particles or Waves
Does radiation need a medium to travel like sound?
No. Light travels in space.
Electromagnetic Radiation uses vibrating …………. instead of vibrating ……………
Uses vibrating fields instead of a vibrating medium.
In electromagnetic Radiation:
The wave moves along?
Magnetic field vibrates in ……… plane.
Electric field vibrates in ………. plane.
The wave moves along the x-axis.
The magnetic field vibrates in the x-z plane.
The electric field vibrates in the x-y plane.
When are electromagnetic waves formed?
When an electric field couples with a magnetic field. The magnetic and electric fields are perpendicular to each other and the direction of the wave.
Does an electromagnetic wave travel slower/faster through a medium compared to a vacuum?
Slower in a medium. Faster in a vacuum.
If a wave has a high frequency what does that tell us about the wavelength?
High frequency, short wavelength.
A low frequency, tall wavelength.
List the electromagnetic spectrum in order of decreasing frequency.
Gamma ray (Highest frequency, shortest wavelength )
X-ray
Ultraviolet
Visible light
Infrared
Microwave
Radio (Lowest frequency, highest wavelength)
What are the colours (7) that make up the visible spectrum.
Their frequencies and wavelengths.
Red (Longest wavelength, lowest frequency + energy)
Orange
Yellow
Green
Blue
Indigo
Violet (Shortest wavelength, Highest frequency + energy)
What are the primary uses for Radio waves, microwaves and Ultraviolet?
Radio waves: Communications
Microwaves: Radar, heating food, industrial applicants
Ultraviolet: Can damage living tissue, numerous medical and industrial applicants.
Definition of a photon.
A packet of light energy.
or The smallest discrete amount of electromagnetic radiation.
(either one! :-1 )
Energy of a photon is related to the …………… of electromagnetic radiation according to h.
Wavelength.
According to Plank’s constant
6,63 x 10^-34 is …………… constant named after?
The two equations are…
Max Plank.
E=hf or E=hxc/landa
h is Plank’s constant, c is the speed of light
How do you figure out gradient of a straight line for a distance vs time graph?
m = At / Ax
gradient is equal to delta time divided by delta position.
How do you figure out speed from the gradient of a straight line?
v = 1/m
speed is equal to one divided by gradient.
