3.3 Electrical Terminology Flashcards
What is the SI unit for voltage?
Volt (V)
Voltage is defined as the number of joules of energy per coulomb of charge.
What does EMF stand for in electrical measurements?
Electromotive Force
EMF is equal to the terminal potential difference when no current flows.
What is the difference between DC voltage and AC voltage?
DC voltage maintains the same polarity over time; AC voltage changes magnitude and polarity over time.
What is the symbol used for electric current?
I
The ampere is the unit for measuring electric current.
What is the SI unit for electric current?
Ampere (A)
1 ampere = 6.24 × 10^18 electrons/second.
Fill in the blank: The higher the __________ of the supply, the higher the current will be for a given electrical resistance.
EMF
What does electrical resistance measure?
Opposition to the flow of electric current.
What is the SI unit for resistance?
Ohm (Ω)
How does the shape of a conductor affect resistance?
Resistance increases where conducting material narrows.
What is electrical conductance?
The effectiveness of current conduction, measured in Siemens (S).
What is the relationship between conductance and resistance?
Conductance is the reciprocal of resistance.
What is the symbol for electrical charge?
Q
The unit for electrical charge is the Coulomb (C).
Fill in the blank: 1 coulomb = 1 __________.
ampere-second
What is conventional current flow?
The flow direction of positive charges from the positive to the negative pole.
What is the difference between conventional current flow and electron flow?
Conventional current flow is from positive to negative, while electron flow is from negative to positive.
What is the purpose of a voltmeter?
To measure voltage across two points in a circuit.
Common voltage for typical aircraft AC power?
115 V
Common voltage for typical aircraft DC power?
28 V
What happens when a voltage is applied across a conductor?
Electrons move from the negative to the positive pole.
How is electrical charge (Q) calculated?
Q = I × t
Where I is current in amperes and t is time in seconds.
What is the effect of collisions between electrons and ions in a conductor?
Electrons lose speed, causing a rise in temperature of the conductor.
What are common current ratings for electrical appliances in households?
100 mA/50 A
What is the decimal factor for the SI prefix ‘mega’?
1 000 000 (10^6)
What is the voltage of a single-cell battery?
1.5 V
What does a high resistance indicate about conductance?
Low conductance
What type of current is an electric current that periodically changes its direction?
AC (Alternating Current)
What is the voltage range for overhead-line systems?
6 kV to 380 kV
What is the unit for measuring conductance?
Siemens (S)
What are the two kinds of electric voltage?
DC voltage and AC voltage
