P6-Waves Flashcards
What do waves do?
They transfer energy without transferring matter
What are the 2 types of waves? (Not longitudinal and transverse)
Mechanical waves (such as sound, water and seismic waves) and Electromagnetic waves (all forms of light waves).
What is the rest position?
The undisturbed position of particles or fields when they aren’t vibrating
What is displacement?
The distance that a certain point in the medium has moved from its rest position
What is the peak?
The highest point above the rest position
What is the trough?
The lowest point below the rest position
What is the amplitude?
The maximum displacement of a point of a wave from its rest position
What is the wavelength?
The distance covered by a full cycle of the wave, usually measured from peak to peak/trough to trough
What is wave period?
The time taken for a full cycle of the wave, usually measured from peak to peak, or trough to trough
What is wave frequency?
The number of waves passing a point each second
What is the formula linking wave period and frequency?
Period = 1/Frequency
T=1/f
What is wave period measured in?
Seconds
s
What is wave frequency measured in?
hertz
Hz
What is the formula linking wave speed, frequency and wavelength?
Wave speed = Frequency x Wavelength
v=fλ
What is wave speed measured in?
metres per second
m/s
What is wavelength measured in?
metres
m
What are the characteristics of longitudinal waves?
- Oscillations are in parallel with the wave direction
- A medium is needed for waves to move
- Examples are sound and seismic waves
- They have compressions and rarefractions
What are the characteristics of transverse waves?
- Oscillations are perpendicular to the wave direction
- No medium is needed for waves to move
- Examples are electromagnetic and water waves
- They have peaks and troughs
What is the law of reflection?
The angle between the incident and normal is the angle between the normal and reflected
What is the angle of incidence?
The angle between the incident ray and normal
What is the angle of reflection?
The angle between the reflected ray and the normal
What is the normal line?
An imaginary line perpendicular to the reflective surface?
How are mirrors drawn?
With a straight line on the side that reflects and diagonal lines on the other side
What are the virtual rays drawn with?
Dotted lines
What is reflection from a smooth flat suface called?
Specular reflection
What is reflection from a rough surface called?
Diffuse reflection
What is an image in a mirror?
Upright, Laterally inverted and virtual
What is refraction?
The direction of a wave as it crosses the boundary between 2 media in which the wave travels at different speeds.
What are wave fronts?
Lines that represent the position of different waves
Where does light refract when it enters a more dense medium?
Towards the normal
Where does light refract when it enters a less dense medium?
Away from the normal
What is the order of the elecromangnetic spectrum from the longest to the shortest wavelength?
- Radio waves
- Microwaves
- Infrared waves
- Visible light
- Ultraviolet rays
- X-rays
- Gamma rays
What is the speed of electromagnetic waves?
300 million m/s
How does energy change down the electromagnetic series?
It increases
What can radio waves penetrate through?
Anything but the ionosphere
What can microwaves penetrate through?
Anything
What can infrared rays pass through?
Most things though stopped by most solids apart from glass
What can visible light pass through?
Anything apart from opaque objects
What can ultraviolet waves pass through?
Everything apart from solids and the ozone layer
What can x-rays pass through?
Anything apart from high density solids e.g. bone and metal
What can gamma rays pass through?
Anything
What rays heat up objects?
Radio waves, Micro waves and Infrared waves
What rays ionise objects?
Ultraviolet rays, X rays and Gamma rays
Radio waves: What are they used for and what are their dangers?
- Used to transmit radio/television programs over large distances
- None known
Microwaves: What are they used for and what are their dangers?
- Used to cook food by heating up water molecules as well as transmitting signals between satellites and mobile phones
- Can cause heating of bodily tissues
Infrared waves: What are they used for and what are their dangers?
- Night vision, Security systems, Remote controls
- Heating absorbed by the skin causing burns
Visible light: What is it used for and what are their dangers?
- Seeing, Cameras, Fire optic communications
- No dangers
Ultraviolet waves: What are they used for and what are their dangers?
- Used in sunbeds, security coding and detecting forged bank notes
- Skin cancer, damage to eyesight
X-rays: What are they used for and what are their dangers?
- X-ray machines
- May lead to cancer
Gamma rays: What are they used for and what are their dangers?
- Used for sterilising medical equipment
- High doses can kill cells
For a concave lense where is the focal point?
Behind the lens (a virtual focus)
Outside 2F: Where is the image position, is it magnified/diminuished, is it upright/inverted, is it real/virtual?
- Between F and 2F
- Diminuished
- Inverted
- Real
At 2F: Where is the image position, is it magnified/diminuished, is it upright/inverted, is it real/virtual?
- 2F
- N/A
- Inverted
- Real
Between F and 2F: Where is the image position, is it magnified/diminuished, is it upright/inverted, is it real/virtual?
- Outside 2F
- Magnified
- Inverted
- Real
At F: Where is the image position, is it magnified/diminuished, is it upright/inverted, is it real/virtual?
- No image
- N/A
- N/A
- N/A
Inside F: Where is the image position, is it magnified/diminuished, is it upright/inverted, is it real/virtual?
- Anywhere
- Magnified
- Upright
- Virtual
What does the colour on a surface depend on?
The wavelengths of light the pigments absorb.
What does a translucent object do to light?
Scatters and refracts it
What is the range of human hearing?
20-20000 Hz
What are the uses of ultrasound?
- Breaking kidney stones
- Cleaning jewellery
- Images of unborn babies
What are the 2 types of seismic waves?
Primary (P-waves) and Secondary (S-waves)
What are the properties of P waves?
- Longitudinal wave
- Fast relative speed
- Can travel through solids and liquids
What are the properties of S waves?
- Transverse wave
- Slow relative speed
- Can travel through solids only
What colours emit the most infrared radiation starting from the most?
- Matt black
- Shiny black
- Matt white
- Shiny silver
What is the cube called in the black body practical?
The Leslie cube
What happens to the peak intensity of radiation as the temperature increases?
The peak intensity moves to shorter wavelengths
What is a perfect black body?
An object that absorbs and re-emits all radiation that is incident on it-it doesn’t reflect any radiation
How are radio waves created?
- Produced by oscillation in electric circuits-transmitter
- When they are absorbed by a reciever, they create an alternating current
- The electrical current has the same frequency of the radio waves
- Displayed by oscilloscopes
What are the three types of radio waves?
- Long wave
- Short wave
- Very short wave
