P5 - Waves in Matter Flashcards
What is an amplitude?
The displacement from the rest position to a crest or trough
What is a wavelength?
A full cycle of the wave
What is a frequency and what is it measured in?
- It is the number of complete waves passing a certain point per second
- It is measured in hertz (Hz)
What is a period of a wave?
The number of seconds it takes for one full cycle
How do vibrations travel in transverse waves?
-The vibrations are perpendicular to the direction the wave travels
How do vibrations travel in longitudinal waves?
-The vibrations are parallel to the direction the direction the wave travels
Can transverse waves travel through liquids?
They can travel on surface of a liquid but can’t travel through liquids
How do longitudinal waves travel in the air?
The waves squash up and stretch out the arrangement of particles in the medium they pass through. They make compressions and rarefactions
What is the wave speed equation?
Wave speed (m/s) = frequency (Hz) x wavelength (m)
What are the properties of electromagnetic waves
- They are transverse waves
- They travel at the same speed through air or space
- They transfer energy from a source to an absorber
- They can be reflected by shiny surfaces
How is the EM spectrum designed
From long wavelength with a low frequency which is not ionising to a short wavelength with high frequency which is ionising
What can we detect from the spectrum?
With our eyes we can detect only a small part of this spectrum which is visible light in different colours.
How are radio waves used for television and radio communication?
Alternating currents in electrical circuits cause charges to oscillate. This creates an oscillating electric and magnetic field which creates a radio wave
Radio waves cause charged particle to oscillate and if they are part of a circuit they induce an ac of the same frequency as the radio wave.
How are microwaves used in satellite communications and what are microwaves used for?
They communicate to and fro satellite as they can pass easily through the Earth’s watery atmosphere
- Used for, cooking food, mobiles and satellite communication
There are different wavelengths of microwaves to cook and for satellites
Describe the reflection and refraction of radio waves
-Waves with long wavelengths and low frequency indergo most refraction in the ionosphere
Describe uses of infrared rays
- Heating
- Cooling
- TV remotes
- night vision
How do optical fibres work?
They work by bouncing light off the sides of a very narrow core. The pulse of light enters the core at a certain angle at one end and is reflected again and again until it emerges at the other end
What are optical fibres used for?
Telephone and internet cable and medical purposes to see inside the body
What are the hazards and the uses of ultraviolet
The uses:
-Energy efficient lamps
-tanning salons
-counterfeit detections
The hazards:
- Causes damage to the DNA in skin cells
-Causes skin cancer
-Causes premature aging of skin
What are the hazards and uses of x-rays
The uses:
-Medical imagery
-Security
The hazards:
-Cause cell damage
-Can cause mutations in cells which cause cancer
What are the uses and hazards of Gamma Rays
Gamma rays are used to detect cancer with radiotracers and can kill cancer.
Hazards are that it can cause cancer
How is it used in detecting fractures?
How is X-Ray used for medical imaging?
- The film is placed below the part of the body which is being X-rayed
- X-ray is transmitted through soft tissue but absorbed by bones
- This then causes the film to go white where the X-ray has not transmitted which shows the bones
How is it used to see an image of a baby in the uterus?
How is Ultrasound used for medical imaging?
- Ultrasound can pass through the body but it is partially reflected at boundaries between tissues
- The reflections are processed by a computer to produce an image
- You can calculate the distance of the bounday when you know the speed of it and the computer knows how long the wave took to be reflected
Which colour refracts the most and why?
Violet refracts the most and red refracts the least because violet has the shortest wavelength so then it refracts the most and it travels the slowest
