CHAPTER 6 Electricity 6.1 Conductors and current flow


In some elements the orbiting electrons in the outer shell are loosely bonded (i.e. the attraction that the positive nucleus has on those electrons is relatively small) and are known as free electrons.


Tese free electrons experience an attraction towards neighbouring atoms and quite easily move into orbit around them. When this happens, the atom from which the electron came is leſt with a net positive charge (positive ion) which causes it to attract electrons from other atoms. Tis random movement of electrons from atom to atom takes place naturally.


Elements with free electrons are classed as good conductors. 6.1.1 Current flow in a conductor


To illustrate this, fig. 6.1(a) represents an enlarged view of a metal rod. Te circles with crosses represent positive ions. Te black dots represent the free electrons and the lines represent the paths of the random movement of the free electrons. Tere is no resultant driſt of electrons in any direction.


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(a) Fig. 6.1 Movement of electrons


If a cell is connected across the ends of the conductor, a potential difference will exist,i.e. one end will be positive and the other negative. Te free electrons will be attracted towards the positive end and they will driſt in that direction. • This driſt of electrons in a specific direction is known as electrical current flow. • The electrons flow from negative to positive and is known as electron flow.


(b)


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