Electrics 1 Charge and static energy Flashcards
In an atom, what is positive, neutral and negative
Proton +
Neutron -
Electron
Lithium atom contains
- Electrons = 3
+ Protons = 3
X Neutrons = 4
Electrons move at what speed?
near the speed of light 186.000 miles per sec (299.792.458meters per sec)
What weak bond would suggest that a material is a good conductor.
Covalent bond
Six basic ways to provide the force to move electrons:
Friction – Static electricity
Chemical action – cells and batteries
Magnetism* – Generators and alternators
Heat – Thermocouples
Light – Photo electric cell
Pressure – piezo electric crystals
EMF
PD
Electromotive force
Potential difference
What is the forumula for ohms law
V = I x R
Current is represented by, and the unit is?
Amp
A
I (impedance)
A volt is a measure of __________ ________
electrical pressure
Ohm is the measure of __________ __ ____
resistance to flow
R
Ω
Frequency is measured in?
Hertz
Electrical power is measured in?
Watts
Capacitance is the ability to store charge and is measured in
Farads
kilofarad x 1000
megafarad x 1,000,000
Power equation PIE
Power = Current x Voltage
watts = amps x EMF
Light aircraft are AC or DC and what voltage?
DC
12 or 24
Large aircraft also have an AC or DC system?
AC
And aircraft battery must supply how much time in the event of an emergency?
30mins
Describe the conductivity of a material with tightly bound electrons
Poor conductors
Describe the conductivity of a material with a large number of free electrons
Good conductor
Examples of good conductors are:
Cupper
Aluminium
Gold
Silver
Examples of poor conductors
Plastic
rubber
wood
dry air
The accumulation of electric charge on an object is known as
Static electricity
Static can build on aircraft, why and when?
Flying through dry air including dry ice crystals
What on an aircraft, that need checking pre-flight, is to do with static electricity?
Static discharge wicks are flexible wires
Trailing edge to control the static discharge back to the atmosphere
To ensure the aircraft has no potential difference, what must you do to parts of the airframe?
Bond it together
Excessive radio interference or other electrical interference could be caused by ____ __________ _______
poor electrical bonding
Static wicks are not perfect. After landing there may still be a _________ __________ between the aircraft and the ground
potential difference
Why do we earth an aircraft while fuelling?
Prevent any arcing between airframe and fuel nozzle
A well bonded airframe can be used as a ______ _____ ______ for all electrical components or circuits.
common earth return
