CTS EXAM: KEY AND LATEST A+ QUESTIONS AND
ANSWERS
o Resistance
- opposition to electron flow
Impedes current and dissipates power as heat
o Impendence
Resistance and reactance
Only AC current
o Power
- rate which work is done (W)
Energy expended manifests itself in another form (i.e. heat, light, motioned.)
o Circuits
Source- supplier of power, info, signal
Load - receiver of info, etc.
Note: current seeks to return to the source, NOT GROUND
Series - voltage divided between the loads
Parallel - current divided between the loads
• Voltage is the same across
Grounding
connects electrical equipment and wiring to reference point then to ground
• Purpose - limits human exposure to high voltage
• Equipment grounding
practice of connecting all metal units used to carry power cables or electricity to ground
o Because metal -> if came in contact with live wire, the whole thing would carry current
o Often connected to ground wire in the infrastructure, that then goes to Earth
• Don't carry current unless needed
• System grounding
AC power circuit and run conductor into earth
Electrical Power
• Power supplies to building..?
,• Power supplies needed to convert AC power that comes into building to DC power that
most devices use
• Isolated grounding circuit
power system solely used for equipment enclosure
o Equipment is grounded via insulated grounding enclosure (NEC 250.96B)
• Man distribution Panel
central location
o Where all power controlled
o Distributes to all locations using feeders and subpanels
• Subpanels
o Use branch circuits to run to outlets, racks, communication equipment, etc.
Branch circuits only used by AV system, not everyone use
o Circuit breakers limit amount of current to any one circuit
• Safety power Tips
o Don't exceed 80% of capacity to any circuit
o Use grounding conductors
o Discard equipment where grounding has been removed
o Never "daisy chain" power strips together.
o Signals
Can be audio, video, control, etc.
Made up of current and voltage
o Signal flow
Traceable path of signals through a system
Separate signal flows for audio, video, control
o Wire
- one conductor
Carries voltage or electronic signal
o Insulation
- dielectric
Stores electric charge
Strength - amount of voltage insulation can take before breaking down
,o Cable
- contains multiple wires
o Conductors
Classified by
• Size
• Construction
• Conductive material
conductor types:
Solid is cheaper than stranded
• Beware of bend radius
• Inflexible, but good strain resistance
Stranded
• More expensive
• Flexible
• Larger
• Flex life - number of times cable can be bent before breaking
Shields
• Types
o Foil - Al sheet
o Braiding - interwoven wires covering insulated wires
o Combo of both
• When selecting, consider:
o Coverage - % of inner cable covered
o Flexibility
o Frequency range - can't protect from full EM and RF interference - pick range you'll be
dealing with
o Jacket
Polyethylene for outdoors (highly flammable)
Teflon - high heat
, o Signal Integrity
Capacitance
property of circuit that opposes any change in voltage
• Ability of non-conductive material to become charged
• Distorts signal
• Any two conductive materials separated by a non-conductive material produces
capacitance
• Stores electric charge in electrostatic field
• Wires pick up on each other’s
Protection
• Separate cables into groups, then separate groups
• Avoid cables near electrically noisy sources
o i.e. motors, lights, power systems, radio
• Analog more susceptible than digital
Distance limits
• Depends on bandwidth and signal level
• Analog can go farther than digital
o Switcher
- ability to choose between two or more sources and send that info to a certain
destination
can be passive (no power needed)
many are active and amplify
Matrix switcher
- composite of many switches
• Allows any input to be connected to any one, several, or all outputs
Types of switchers
• Mechanical - mechanical connection between cables
o No attention to phase of signals
• Smooth - monitors sync info for second signal
ANSWERS
o Resistance
- opposition to electron flow
Impedes current and dissipates power as heat
o Impendence
Resistance and reactance
Only AC current
o Power
- rate which work is done (W)
Energy expended manifests itself in another form (i.e. heat, light, motioned.)
o Circuits
Source- supplier of power, info, signal
Load - receiver of info, etc.
Note: current seeks to return to the source, NOT GROUND
Series - voltage divided between the loads
Parallel - current divided between the loads
• Voltage is the same across
Grounding
connects electrical equipment and wiring to reference point then to ground
• Purpose - limits human exposure to high voltage
• Equipment grounding
practice of connecting all metal units used to carry power cables or electricity to ground
o Because metal -> if came in contact with live wire, the whole thing would carry current
o Often connected to ground wire in the infrastructure, that then goes to Earth
• Don't carry current unless needed
• System grounding
AC power circuit and run conductor into earth
Electrical Power
• Power supplies to building..?
,• Power supplies needed to convert AC power that comes into building to DC power that
most devices use
• Isolated grounding circuit
power system solely used for equipment enclosure
o Equipment is grounded via insulated grounding enclosure (NEC 250.96B)
• Man distribution Panel
central location
o Where all power controlled
o Distributes to all locations using feeders and subpanels
• Subpanels
o Use branch circuits to run to outlets, racks, communication equipment, etc.
Branch circuits only used by AV system, not everyone use
o Circuit breakers limit amount of current to any one circuit
• Safety power Tips
o Don't exceed 80% of capacity to any circuit
o Use grounding conductors
o Discard equipment where grounding has been removed
o Never "daisy chain" power strips together.
o Signals
Can be audio, video, control, etc.
Made up of current and voltage
o Signal flow
Traceable path of signals through a system
Separate signal flows for audio, video, control
o Wire
- one conductor
Carries voltage or electronic signal
o Insulation
- dielectric
Stores electric charge
Strength - amount of voltage insulation can take before breaking down
,o Cable
- contains multiple wires
o Conductors
Classified by
• Size
• Construction
• Conductive material
conductor types:
Solid is cheaper than stranded
• Beware of bend radius
• Inflexible, but good strain resistance
Stranded
• More expensive
• Flexible
• Larger
• Flex life - number of times cable can be bent before breaking
Shields
• Types
o Foil - Al sheet
o Braiding - interwoven wires covering insulated wires
o Combo of both
• When selecting, consider:
o Coverage - % of inner cable covered
o Flexibility
o Frequency range - can't protect from full EM and RF interference - pick range you'll be
dealing with
o Jacket
Polyethylene for outdoors (highly flammable)
Teflon - high heat
, o Signal Integrity
Capacitance
property of circuit that opposes any change in voltage
• Ability of non-conductive material to become charged
• Distorts signal
• Any two conductive materials separated by a non-conductive material produces
capacitance
• Stores electric charge in electrostatic field
• Wires pick up on each other’s
Protection
• Separate cables into groups, then separate groups
• Avoid cables near electrically noisy sources
o i.e. motors, lights, power systems, radio
• Analog more susceptible than digital
Distance limits
• Depends on bandwidth and signal level
• Analog can go farther than digital
o Switcher
- ability to choose between two or more sources and send that info to a certain
destination
can be passive (no power needed)
many are active and amplify
Matrix switcher
- composite of many switches
• Allows any input to be connected to any one, several, or all outputs
Types of switchers
• Mechanical - mechanical connection between cables
o No attention to phase of signals
• Smooth - monitors sync info for second signal
