Chapter XXII: Appendix: O

SOME ELECTRICAL SYMBOLS, TERMS AND FORMULAS

Symbols Terms

E or EMF = Electromotive Force
I = Intensity of Current
R = Resistance
C = Capacity
Q = Quantity of Current
[F] = Magneto-Motive Force
[R] = Reluctance (magnetic resistance)
µ = Magnetic Permeability
W = Electric Energy
P = Electric Power

SOME DEFINITIONS

E or EMF, or _electromotive force_, is the force that moves a current through a conductor.

I, or _intensity of current_, or _current_ as it is called for short, is the flow of electricity through a conductor.

R, or _resistance_ is that property of a conductor which opposes the flow of the current.

SOME ELECTRICAL UNITS

_Practical Units._ _Electrical Quantity_

Volt is the practical unit of EMF
Ampere is the practical unit of I
Ohm is the practical unit of R
Watt is the practical unit of P

OHM’S LAW

Since the intensity of an electric current varies _directly_ as the electromotive force and _inversely_ as the resistance, if you know the value of any two of the above units you can easily find the third.

Volts E
Amperes = -------, or I = ---
Ohms R

Current I
Electromotive Force = ------------, or E = ---
Resistance R

Electromotive Force E
Resistance = ---------------------, or R = ---
Current I

_To Find Power of an Electric Current in Terms of Horse Power_

One Watt = 1 volt × 1 ampere
746 Watts = 1 horse power.

To find the power of an electric current in terms of horse-power, find the number of watts by multiplying the volts by the amperes and divide the watts by 746 and the result will give you the horse-power of the current.