2016-E6F: Optical components: photoconductive principles and effects, photovoltaic systems, optical couplers, optical sensors, and optoisolators; LCDs
What is photoconductivity?
The increased conductivity of an illuminated semiconductor
The conversion of photon energy to electromotive energy
The conversion of electromotive energy to photon energy
The decreased conductivity of an illuminated semiconductor
What happens to the conductivity of a photoconductive material when light shines on it?
It stays the same
It becomes unstable
What is the most common configuration of an optoisolator or optocoupler?
An LED and a phototransistor
A lens and a photomultiplier
A frequency modulated helium-neon laser
An amplitude modulated helium-neon laser
What is the photovoltaic effect?
The conversion of light to electrical energy
The conversion of voltage to current when exposed to light
The conversion of electrical energy to mechanical energy
The tendency of a battery to discharge when used outside
Which describes an optical shaft encoder?
A device which detects rotation of a control by interrupting a light source with a patterned wheel
A device which measures the strength of a beam of light using analog to digital conversion
A digital encryption device often used to encrypt spacecraft control signals
A device for generating RTTY signals by means of a rotating light source
Which of these materials is affected the most by photoconductivity?
A crystalline semiconductor
An ordinary metal
A heavy metal
A liquid semiconductor
What is a solid state relay?
A device that uses semiconductors to implement the functions of an electromechanical relay
A relay using transistors to drive the relay coil
A mechanical relay that latches in the on or off state each time it is pulsed
A passive delay line
Why are optoisolators often used in conjunction with solid state circuits when switching 120VAC?
Optoisolators provide a very high degree of electrical isolation between a control circuit and the circuit being switched
Optoisolators provide a low impedance link between a control circuit and a power circuit
Optoisolators provide impedance matching between the control circuit and power circuit
Optoisolators eliminate the effects of reflected light in the control circuit
What is the efficiency of a photovoltaic cell?
The relative fraction of light that is converted to current
The output RF power divided by the input DC power
The effective payback period
The open-circuit voltage divided by the short-circuit current under full illumination
What is the most common type of photovoltaic cell used for electrical power generation?
What is the approximate open-circuit voltage produced by a fully-illuminated silicon photovoltaic cell?
What absorbs the energy from light falling on a photovoltaic cell?
What is a liquid crystal display (LCD)?
A display utilizing a crystalline liquid and polarizing filters which becomes opaque when voltage is applied
A modern replacement for a quartz crystal oscillator which displays its fundamental frequency
A frequency-determining unit for a transmitter or receiver
A display that uses a glowing liquid to remain brightly lit in dim light
Which of the following is true of LCD displays?
They may be hard view through polarized lenses
They are hard to view in high ambient light conditions
They only display alphanumeric symbols
All of these choices are correct
● = Unseen
● = Weak
● = Review
● = Learned
● = Incorrect answer