Electromagnetic Waves Flashcards
(17 cards)
What is the equation for intensity loss with distance from a source?
I = kF2
Where k is the intensity at the center of the waves
How does intensity change when the distance from the source is doubled?
Intensity becomes a quarter of the original value
What part of the electromagnetic spectrum can human eyes detect?
Visible light, from deep red (A = 740nm) to indigo blue (A = 370nm)
What is the speed of light represented by in equations?
c = 3 x 10^8 ms^-1
Fill in the blank: The electromagnetic spectrum ranges from _______ to gamma rays.
radio waves
What can infrared and longer wavelengths be used for?
Various communications purposes
What frequencies are used for satellite communications?
Higher frequencies
What happens to wavelengths above about 30 m in the atmosphere?
They are reflected by a layer of charged particles
What is the significance of the atmospheric opacity for broadcasting?
It affects the ability to broadcast certain frequencies
What do you need to memorize for the electromagnetic spectrum?
Either the wavelengths or the frequency range for each part
True or False: High frequencies carry less data than low frequencies.
False
What type of wave-fronts do directional beams have?
Flat plane wave-fronts
How do spherical wave-fronts lose intensity?
They lose intensity with radius according to the equation I = kF2
What is the relationship between frequency and wavelength in the electromagnetic spectrum?
c = fA
What are the dangerous ionizing radiations that are strongly absorbed by the atmosphere?
Gamma rays and X-rays
What is the wavelength range for visible light?
400 nm to 700 nm
Fill in the blank: UHF, VHF, AM radio, and microwave are types of _______.
radio waves
