P1 Flashcards
What are waves?
- A regular disturbance that transfers energy
- The amplitude- displacement from the rest position to a peak or trough
- The wavelength is the distnace between the same two adjacent disturbances(one full cycle of the wave)
- Frequency - number of complete wavaes made by a source-hz(1 wave per second)
- Period- the number of seconds it takes for one full cycle to pass a certain point - period= 1/frequency
What are transverse waves?
- The disturbance of the medium is perpendicular(at 90 degrees) to the direction of wave travel
- Electromagnetic and s waves are transverse
What are longituidinal waves?
- The disturbance of the medium is parellel to the direction of wave travel
- sound waves and p waves are longitudinal
- They squash up and stretch out the arrangement of particles in the medium they pass through making compressions and rarefractions
What are longituidinal waves?
- The disturbance of the medium is parellel to the direction of wave travel
- sound waves and p waves are longitudinal
- They squash up and stretch out the arrangement of particles in the medium they pass through making compressions and rarefractions
What is the wavespeed equation?
Wavespeed(m/s)=Frequency(Hz) x Wavelength(m)
What is reflection?
- When a wave is sent back to way it comes
- Angle of incidence=Angle of reflection
What is refraction?
- When a wave hits a boundary at an angles, but there is a change of speed when this happens and causes a change in direction
What is the electromagnetic spectrum?
- A spectrum of 7 waves:Radio, microwaves, infrared,visible, ultraviolet, x-ray, gamma
- Radio has the largest wavelength and gamma has the smallest
- Frequency and energy are highest at the bottom of the list and lowest at the top of the list
- Ultraviolet, xray and gamma rays are the only ionising waves on the spectrum
What are Radio waves used for?
- They are used for communication
What are microwaves used for?
- Cooking and communication
- The waves penetrate into the food before being absorbed and transferring energy to th water molecules to heat up the food
What is infra red radiation used for?
- It can be used to increase or monitor temperature
- Given off by all objects
What are visible light rays used for?
It is used to help humans be able to see things, and communication using optical fibres
What are ultraviolet waves used for?
Used in fluorescent lamps
What are x rays used for?
Help us view internal structures of objects structures and bodies
What are gamma rays used for?
Used to help sterilize medical instruments and food
What are the two different types of lenses?
Concave and convex lenses
What is a concave lense?
- A lens that caves inwards, causes parallel rays of lights to diverge
- Used in glasses of shortsighted people
What are convex lenses?
- A lense that buldges inwards and cauases parrallel light rays to converge
- Used in the glasses of long sighted people
What are sound waves?
- A wave that transmitts sound that causes objects to vibrate
- Vibrations pass through the surrounding medium as a series of compressions and rarefractions
How do we hear sound in our eardrums?
1)Sound waves reach your eardrums and cause them to vibrate
2)These vibrations are passed onto tiny bones in the ear called ossicles through the semi-circular canal and to the cochlea
3)The cochlea turns these vibrations into electrical signals which get sent to your brain
4)The brain interpretes the signals as sounds of different pitches and volumes, depending on frequency and intensity
What is ultrasound?
- This is sound with frequencies higher than 20, 000Hz
- Above range of human hearing
- Used in medical and industrial imaging like scanning foetuses
What are s waves?
- They are transverse waves that travel at 60% of the speed of p waves
- Can only travel through solids
What are p waves?
- They are a really fast type of longitudinal wave that can travel through solids and liquids
- Faster than s waves
What is absorbing radiation?
- The balance between emitting and absorbing radiation will affect an objects temperature
- When an object is hotter than its surroundings more radiation is emitted than absorbed-will warm up surroundings
- When object is cooler than surrounding less energy emitted than absorbed-surroundings will cool down
- If an object absorbs and emitts the same amount of energy the temperature stays the same
What is intensity?
The power of radiation per unit area
