2.4 - Optics Flashcards
What is light?
A form of electromagnetic radiation
What is visible light measured in?
nanometres (Nm) or Angstrom (A)
What are the wavelengths of Ultraviolet light?
less than 4,000 A
What are the wavelengths of Infrared light?
More than 7,000A
What is the speed of light?
3x10^8 m/sec
What is the formula for the speed of electromagnetic radiation (c)?
c = f x lamda
frequency x wavelength
What is the law of reflection?
The angle of incidence = the angle of reflection
What happens to refraction at 90 degrees?
There is no refraction
What happens to light wave-fronts when they refract?
They change direction
What is the equation for the focal length of a concave mirror?
f = 1/2 x R (radius of curvature)
What happens to an image in a concave mirror?
(Magnifying bathroom mirror)
What happens to an image in a convex mirror?
Diminished image and fit more detail in (car rear-view mirror)
What are the three parts to a fibre optic data link?
Transmitter, receiver and optical fibre.
What are the two basic types of fibres?
Multimode and single-mode
What is the cladding layer of an optical fibre?
A dielectric material reducing the loss of light into surrounding air, adds mechanical strength, reduces scattering at the surface of the core and protects the fibre from absorbing surface contaminants.
What is Attenuation?
The loss of optical power as light travels along the fibre.
What is bandwidth?
The amount of information that can be transmitted at one time.
What is the SI unit of luminosity?
Candela
What source of light do lasers use?
Coherent light
What is meant by a fibre optic cable which is attenuated at 29dB/m?
This is the figure allowed when calculating power gain in a fibre optic cable
What type of fibre optic cables are used in a flying control system?
Multi mode fibre
What speed of light are fibre optic cables capable of transmitting light at?
1.99 x10^8 m/s (lower than speed of light in a vacuum)
