EM wVes Uses Flashcards
(20 cards)
Radio waves
Used for long range communication because they can be reflected from the earths atmosphere and travel long distance distances
Microwave
Use in satellite communications because microwaves can penetrate earths atmosphere
Infrared
Used an optical fiber communications because they can undergo total internal reflection
Visible light
Used them taking photos and videos because cameras are set up to detective visible light
Ultraviolet
Used for detecting security Inc. because it fluoresces with UV light
X-rays
Used to photograph bones because x-rays can penetrate soft tissues, but not bones
Gamma rays
Used to sterilize medical tools because gamma kills bacteria
Dangers of radio waves microwaves, and infrared waves
High intensity microwaves can cause heating of internal organs because water molecules and absorb microwave strongly
Dangers of gum and x-rays and possibly ultraviolet
Gamma and x-rays and high intensity UV can harm cells and cause cancer because they are highly ionizing due to having a lot of energy
What are electromagnetic wave?
They transfer waves that transfer energy from the source of the waves to an absorber
Radiation with higher energy is:
Highly ionizing and harmful to cells and tissues, causing cancer
What is visible light?
It’s defined as the range of wavelengths which are visible to humans. it is the only part of the spectrum detective ball by the human eye. On,y takes up 0.0035%
Red - longest wavelength, and violet shortest wavelength
ROYGBIV
Energy transfer by microwave
Water molecules absorb certain wavelength of microwave radiation therefore, microwave ovens transfer energy by radiation to the thermos store of the food placed inside it
Energy transferred by infrared
All hot objects, an infrared radiation. The omitted waves can then be absorbed by other objects, warming them up, so therefore energy is transferred by radiation to the thermal store of the object.
Energy transfer from the sun
The sun emits several types of EM radiation, including visible lights, infrared waves, and ultraviolet waves
What happens when an electromagnetic wave hits an atom?
It can be absorbed by one of the electrons giving an energy which causes the electron to move up to a higher energy level
What happens if an electron moves down to a lower energy level?
It will emit an electromagnetic wave in the process, and this way atoms can absorb and emit electromagnetic waves over a wide range of. Frequencies
How can radio waves be produced?
By connecting an antenna to a high frequency, alternating current power source. The oscillation of charge in the alternating current circuit produces radio waves with the same frequency of oscillation
What happens in the transmitting antenna?
The charge from the AC oscillate up and down the antenna producing radio waves that can be absorbed by similar aerial some distance
What happens in the receiving aerial?
The metal absorbs the radio waves creating an AC with the same frequency as the transmitted wave
