3.3 Electrical Terminology Flashcards
What does the SI prefix giga represent ?
10x^9 or 1,000,000,000
What does the SI prefix mega represent?
10x^6 or 1,000,000
What does the SI prefix kilo represent?
10x^3 or 1,000
What does the SI prefix milli represent?
10x^-3 or 0.001
What does the SI prefix micro represent?
10^-6 or 0.000 001
What does the SI prefix nano represent?
10x^-9 or 0.000 000 001
What does the SI prefix pico represent?
10x^-12 or 0.000 000 000 001
What is the difference between MW and mW in relation to the SI prefix?
MW is mega watts 10x^6 and mW is milli watts 10x^-3
What is voltage?
Is a measure of the difference in electrical charge between two points
What is voltage also referred to as in simpler terms?
Electrical pressure
What is the SI unit for voltage?
Volts
What is the equation for voltage?
V= E/Q
(V=voltage, E=energy transferred in joules, Q= charge in coulombs)
What are the two types of electric voltage?
Direct current (DC) voltage and Alternating current (AC) voltage
What are all voltages classified as?
Potential difference (PD) or an Electromotve Force (EMF)
How do you define DC voltage?
If voltage maintains the same polarity over time even if the value changes
How do you define AC voltage?
If a voltage magnitude and polarity change over time
What is electromotive force (EMF)?
The voltage of the supply and is a measure of the energy transferred to the circuit
What is potential difference?
A measure of the energy transferred from electrical energy to other forms of energy when a current flows (bonding check)
How is a voltmeter set up?
In parallel wit the terminals of a power source and/or a load
What are the two different ways to indicate the measured voltage?
-pointer deflection (analogue)
-numerical read-out (digital)
Why is it said that voltmeters don’t have current flow through them?
They have a very high resistance (considered infinite in calculations)
How many volts is a typical aircraft AC power supply?
115v
How many volts is a typical aircraft DC power supply?
28v
What are the typical volts of a single cell battery?
1.5v
What is electric current?
The number of coulombs of charge flowing through the cross section of a conductor in one second
What is the unit for current?
Ampere (amps)
What symbol is used for current?
I
What has an effect on the current being higher or lower?
The Electromotive force (EMF) and the resistance of the circuit
What does the speed of movement of electrical charges depend on?
-conductor material
-conductor cross-section
-potential difference
-temperature
What is used to measure electric current?
An ammeter (ampere meter) or current meter
Electrical resistance is said to be the opposite of?
The opposite to flow of electric current
What does electrical resistance measure?
How much energy is required to case a current to flow
When resistance is high what happens to the potential difference?
To obtain the same current it must be increased
What are the units for resistance?
Ohms Ω
What are the units for voltage?
Volts V
What are the units for current?
Ampere A
Why is temperature given off from a conductor when electricity is passed through?
Because the electrons collide with the ions to cause friction and produce heat
When you apply voltage what direction do the electrons travel in?
Negative to positive
If there was only electrons in a conductor what would happen if a voltage is supplied?
Their movement would accelerate
How does cross sectional area of a conductor affect the resistance of the conductor?
The resistance goes up when the conductor get’s narrower
If a something has a high resistance what is the conductance said to be?
Low
If something has a low resistance what is the conductance said to be?
High
Conductance is reciprocal to?
Resistance
What is conductance measured in?
Siemens
When you apply voltage to circuit what direction does the current flow?
Positive to negative
What is conventional current flow?
The direction in which positive charges move
Why is conventional current flow only found in liquids and gases?
Because the positive charges in metals are fixed in place
What decides the direction that electrons travel in?
The polarity of the applied voltage
The polarity of the applied voltage
What does an electrical supply do?
It separates charges by by forcing electrons from the positive to the negative
