Electromagnetic Waves Flashcards
Do all electromagnetic waves travel at the same speed in a vacuum?
Yes
Which has the shortest wavelength and longest frequency?
Gamma rays
What has the longest wavelength and lowest frequency?
Radio waves
The higher the frequency of an electromagnetic wave…
The more energy it transfers
State the spectrum starting with the wave with the shortest wavelength and longest frequency?
Radio microwaves infrared light UV X-rays and gamma
What is the wave speed of electromagnetic waves when traveling through space?
300 million m/s
What are microwaves used in?
Communications. Microwave transmitters produce wavelengths that are able to pass through the atmosphere they are used to send signals to and from satellites and within mobile phone networks
What are radio waves?
Transmit radio and to programmes and carry mobile phone signals
Are microwaves and radio waves dangerous?
They will penetrate you skin and are absorbed by body tissue and can heat internal organs and damage them
Is infrared radiation dangerous?
It is absorbed by skin and can burn
The shorter the wavelength of the waves…
The more information they carry, the shorter their range, the less they spread out
What is a band?
The radio and microwave spectrum is divided into bands based on purpose
What do we know about the dangers of mobile phones?
Research is needed to evaluate their safety
What are microwaves used for?
Tv signals
What are optical fibres?
Very thin glass fibres. Used to transmit signals carried by visible light or infrared radiation. The signals travel down the fibre by repeated total internal reflection
Why are optical fibres useful?
They carry more information and are more secure than radio waves and microwave transmissions.
How are radio waves produced?
By applying an alternating voltage to an aerial
What is the Doppler effect?
The change in wavelength and frequency of the waves from a moving source due to the motion of the source towards or away from the observer
When the source mo Es away from the observer the observes wavelength …………….. and the frequency …………..
Increases
Decreases
When the source moves towards the observer the observed wavelength …………… And the frequency ………..
Decreases
Increases
What are galaxies?
Large collections of stars
To which end of the spectrum have light observed from distant galaxies been shifted towards?
Red end
What is red shift?
Increase in the wavelength of electromagnetic waves emitted by a star or galaxy due to its motion away from us. The faster the speed of the star or Galaxy the greater the red shift
What would a blue shift indicate?
A galaxy moving toward us
