P 11 Flashcards
What do waves do ?
They transfer energy without transferring matter .
What are the two types of waves ?
Longitudinal and transverse waves
What is a transverse wave ?
All electromagnetic waves are transverse waves . The oscillations of a transverse waves are perpendicular to the direction in which the waves transfer energy .
What is a mechanical wave ?
Vibrations that travel through a medium .
What are example of mechanical waves ?
Sound waves , water waves , waves on springs and ropes and seismic waves produced by earthquakes .
Can a mechanical wave be a transverse or longitudinal wave ?
They can be both
What is an electromagnetic waves ?
These are waves can travel through a vaccum at the speed of 300,000 kilometres per second .
What is are some examples of electromagnetic waves ?
Light waves , radio waves and microwaves
What is a longitudinal wave ?
The oscillations of a longitudinal wave are parallel to the direction in which the waves transfer energy .
What is the amplitude in a wave ?
The maximum displacement of a point on the wave from its undisturbed position .
What is a wavelength in the wave ?
The distance from one wave to another .
What is the peak of the wave ?
The top of the wave
What is the peak of the wave ?
The top of the wave
What is the frequency of waves ?
The number of waves passing a particular point every second .
What is the unit for frequency ?
Hertz (Hz)
What is the period in a wave ?
The period of a wave is the time taken for each wave to pass a fixed point .
What is the equation for the Period of a wave ?
Period = 1/frequency
How do you calculate wave soeed ?
Wavelength x frequency
What two waves can be reflected at the boundary of two different materials ?
Sound and light
What is the incident ray ?
The ray that hits the object from an angle
What is the reflected ray ?
The ray that is reflected from the point at which the incident ray hits in the other direction .
What is the refracted ray ?
When a wave changes speed and direction upon entering a denser or less dense medium . For example a light ray changes direction when refracted by a lens .
What are sound waves ?
The vibrations travelling through the air .
Are sound waves easy to produce ?
Yes
How does a sound wave increase ?
Increase in Temprature
What three things can you do to investigate waves ?
A ripple tank
String
A signal generator and a loudspeaker
What are electromagnetic waves , in depth ?
Electric and magnetic disturbances that can be used to transfer energy from a source to an absorber.
What is the order of the electromagnetic spectrum ?
- X-rays and gamma rays
- Ultra-violet radiation
- Visible light
- Infared
- Micro-waves
- Radio waves
What is the difference between a long and short wavelength ?
Increase in energy and frequency when the waves get shorter
What is white light ?
Light from ordinary lamps and from the sun , this is because it contains all the colours of the spectrum .
Do all objects emit infared radiation ?
Yes
Is this statement true ? , ‘ the hotter the object is , the more radiation it emits ‘ .
Yes
Is infared radiation absorbed by you skin ?
Yes it can damage , burn , or kill skin cells .
What is an optical fibre ?
Thin glass
What is infared radiation used for ?
- To detect tissue that is unhealthy
- To see people in the dark
- To heat objects up quickly
What do people use microwaves for ?
People use microwaves for communication and to heat food faster
What are radio waves used for?
Radio waves are used to carry radio , TV and mobile signals .
Why are microwave and radio waves hazardous ?
They can penetrate peoples bodies and can heat the internal parts of the body .
What is the required practical called for radiation ?
Leslie cube practical
What is a leslie cube ?
A hollow metal box made up of copper steel .
What are the four faces on the leslie cube ?
- Mat black surface
- White surface
- Polished , shiny surface
- Unpolished surface
What is the independent variable in the leslie cube practical ?
The colour and reflectivity of each surface on the cube
What is the dependent variable in the leslie cube practical ?
The temprature
What is the controlled variable for the leslie cube practical ?
The volume of water and the distance between the thermometer and cube.
What is the equipment used in the leslie cube practical ?
Cube , kettle , ruler , heat proof mat and infared thermometer
What is the method used in the leslie cube practical ?
- Pour hot water into the leslie cube until it is full
- Use a ruler to measure 10 cm from one surface of the leslie cube
- Use an infared thermometer to measure the apparent temprature of the surface
- Record the apparent temprature and the colour / reflectivity of the surface
- Repeat for each of the different surfaces
What is visible light used for ?
Used to form images in cameras and video cameras , used in surgery .
What is ultraviolet radiation used for ?
Used for crime evidence , forged bank notes , passports and driving lisences .
What are x-rays used for ?
Used to produce medical images of broken bones .
What are gamma rays used for ?
Similar to x-rays / used to sterilise food by killing bacteria . Can treat cancer .
What are carrier waves ?
Waves that are used to carry any type of signal .
What do the wavelength of waves effect ?
- how far they can travel
- how much they spread
- how much information they carry
What does ultraviolet rays do to the body ?
They are harmful to the human eye and can cause blindness .
How are x rays and gamma rays both similar ?
They are both short wavelengthed and carry more energy
How do x-rays and gamma rays differ ?
X-rays are produced when electrons or other particles moving at high speeds are stopped
Gamma rays can penetrate substances more than x-rays
What are three types of radiation ?
Alpha , beta and Gamma .
What is the radiation dose measured in ?
Sieverts (sv)
