P6 Waves Flashcards
Define longitudinal waves
The direction of oscillation is PARALLEL to the direction of energy transfer
Define transverse waves
The direction of oscillation is PERPENDICULAR to the direction of energy transfer
2 examples of LONGITUDINAL waves
Sound
Seismic P waves
4 examples of TRANSVERSE waves
Water waves
Seismic S waves
Light
EM waves
Waves transfer _____ without transferring ______
ENERGY without transferring MATTER
What is a wave length (M)
The length of one complete wave
What is the time period (S)
The time taken for one wave to pass
What is the frequency of waves (Hz)
The number of waves that pass every second
We can use a ripple tank to find ….
Frequency
How to measure speed of sound waves
-Attach a microphone to an oscilloscope
-Clap once next to microphone
-Measure how long it takes for echo to return the microphone from a wall that is a known distance away
-Use oscilloscope to measure time taken
-Then do total distance divided by time
What is the human hearing range
20hz to 20Khz
If frequency is greater than 20kHz it is known as
Ultrasound
Ultrasound is above __kHz
20
How do we hear sound waves
They cause your eardrum to vibrate, which sends a signal to your brain
How can we use ultrasound to see a baby in a pregnant lady
The ultrasound waves are reflected back when they meet the baby
Seismic P waves or Seismic S waves travel through liquid
Seismic P waves can
Longitudinal waves can or can’t travel through liquid
Longitudinal waves CAN travel through liquid
Transverse waves can or can’t travel through liquid
Transverse waves CANT travel through liquid
Evidence for a molten core in the earth
After an earthquake, P-waves(longitudinal) can be recorded on the other side of the earth, however, S-waves (transverse)cannot so there must be a molten/liquid core
If a light reflects off of a SMOOTH surface, this is
SPECULAR REFRACTION
A rough surface will SCATTER light, this is called
DIFFUSE refraction
Order of Electromagnetic wave spectrum
(R,M,I,V,UV,X,G)
Lower frequency ➡️ Higher frequency
Radio waves
Microwaves
Infrared
Visible light
Ultra Violet
X-rays
Gamma rays
Example of radio wave uses
Phones, TV, Wi-Fi
Example of microwave uses
Cooking (absorbed by water)
Example of infrared uses
Cooking (absorbed by surface)
Example of visible light uses
Vision
Ultra violet uses
Tanning (can cause skin cancer)
Uses of X-rays
Medical scans
(can be dangerous)
Uses of gamma rays
Medical treatments
(Also dangerous)
All EM waves are emitted and absorbed by ______ apart from gamma rays which are emitted by______
ELECTRONS, NUCLEI
UV, GAMMA and X-RAYS are all examples of ___________ radiation
Ionising
Infrared practical - Showing matte black is the best emitter of infrared
-Use a Leslie cube, and fill it with hot water
-Point an infrared detector at each four sides of the Leslie cube, making sure it is an equal distance away from the cube each time
-Matte black is best emitter , then shiny black, then white, then shiny metallic
Infrared RPA - why is an infrared detector better than a thermometer
Higher resolution
Infrared RPA - showing matte black is the best absorber of IR
-Place an infrared heater in between two metal plate, one shiny metallic plate and one matte black
-On the other side of the plates use Vaseline to attach a drawing pin
-Switch on the heater and start timing
-Record time it takes for Vaseline to melt and drawing pins to fall off
-Drawing pin falls of matte black plate first, absorb more IR quicker
When waves enter a new material, their ______ changes, as does their _____ angle. This is known as ______
SPEED, ANGLE, REFRACTION
If the wave slows down when entering an object, it moves toward the_______
Normal
When a wave slows down in an object, the angle of _______ is smaller than the angle of ________
Refraction is smaller than Incidence
Light disperses through a prism because
Different wavelengths are refracted different amounts .
(Blue most, red least)
Real images can be ______ virtual images cannot
PROJECTED
Magnification =
Image height
_________________
Actual height
How do we describe an images
(3 pairs of things)
Real/ virtual
Enlarged/ diminished
Upright/ inverted
An object appears a certain colour because it _____ those wavelengths and _____ others
Reflects, Absorbs
What is a blackbody
A theoretical object that perfectly absorbs and emits all wavelengths of radiation
What can we apply the black body model to as an approximation
Stars and Planets
If the rate of ABSORPTION is greater than the rate of EMISSION, its temperature ______
INCREASES, which in turn increases the rate of emission
We perceive different colours when different _____ of light are _______ by the retina
Wavelengths, Absorbed
