(2) It is possible to pile up electrons at one point and remove them from the

other point by means of a battery or generator. The greater the excess of electrons at

one point and deficiency of electrons at another, the greater is the attraction or

difference in potential between these points.

(3) The unit of measurement of this potential difference is the volt. A volt is

the amount EMF needed to drive a current of one ampere through a resistance of one

ohm.

b. **Current**.

(1) The intensity of electric current is determined by the number of electrons

flowing past a point. in one second. The greater the number of electrons flowing per

second, the greater the value of the current.

(2) The unit of measurement of current strength is the ampere, which is one

coulomb of electricity flowing per second. The unit of quantity of electricity is a

coulomb, which is 6.28 x 1018 electrons. The milliampere (mA) is 1/1000 as large as the

ampere. Thus 6.28 x 1015 electrons (0.001 coulomb) flowing per second is equal to one

mA.

The mathematical shorthand used above is the explained as follows:

101 = 10

105 = 100,000

102 = 100

106 = 1,000,000

103 = 1,000

1012 = 1,000,000,000,000

104 = 10,000

1015 = 1,000,000,000,000,000

Thus, the power to which 10 is raised is equal to the number of zeroes in the fully

written expression.

c. **Resistance**.

(1) In an electric circuit, resistance depends on the type and physical

dimensions of the material making up the circuit. Every conductor resists the flow of

electrons through it. Opposition or hindrance to the flow of electrons in an electric

circuit is called resistance.

(2) The unit measure of resistance is the ohm; it is symbolized by the Greek

letter omega (**Ω**)

MD0950

2-5

Integrated Publishing, Inc. |