Electricity Formulas and definitions. Flashcards Preview

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What are the four basic ohms laws?

1) I=E/R
2) R=E/I
3) E=IxR
4) P=ExI


Ohms law states that:

The rate of flow of the current is equal to electromotive force divided by resistance.


Name the three rules of a series circuit?

1) Total current=The current in any part.

2) Total voltage= The sum of the voltages across all parts of the circuit.

3) Total resistance= The sum of all the parts.


Name the three rules of a parallel circuit.

1) Total current=The sum of the currents in all the branches.

2) Total voltage=The voltage across any branch.

3) Total resistance=Reciprocal of the reciprocal.


Total resistance in a parallel circuit is always _____________ than the resistance in any branch.



What is a combination circuit?

A combination of series circuits and parallel circuits.


What is Kirchhoff’s two laws?

1) The sum of the currents arriving at any point in a circuit must equal the sum of the currents leaving that point.

2) The total voltage applied to any closed circuit path is always equal to the sum of the voltage drops in that path.


What is capacitance measured in and how is the total capacity of capacitors solved for in a series and parallel circuit?

Series: capacity=reciprocal of the reciprocal

Parallel: capacity=The sum of the capacitors.


What does each color on a resistor represent?

1) Digit
2) Digit
3) multiplier
4) Tolerance in percent.


What is inductance measure in and how is total inductance solve for in a series and parallel circuit?

Series: Total inductance=The sum of all inductors.

Parallel: Total inductance=The reciprocal of the reciprocal.


Capacitive loads have ________ currents, and inductive loads have ______________ currents.

Leading currents
Lagging currents


Describe impedance and what it’s measured in.

Impedance is the total opposition to an alternating current. It’s expressed in ohms.


What is reactance and what is it’s symbol?

Reactance is the opposition to an alternating current caused by inductance and reactance.

It’s symbol is “X” and is measured in ohms.


The formula for Inductive reactance.

XL= 6.28 x frequency x inductance.


The formula for capacitive reactance.

Xc= 1/(6.28 x frequency x capacitance)