Electric current

The cross sectional area of the conductor influences the current because a larger cross sectional area means the charge can pass through it more easily.

The type of conductor and its length also have an influence. All of these factors which have an influence are brought together in a magnitude which we call resistance.

Resistance measures the opposition of the conductor to the flow of an electric current. Its unit is called the ohm. All the elements in a circuit have their own resistance. When we study Ohm's Law we will see the important role that it plays.

In the visual, try to see the relation of resistance with length, diameter and the type of conductor (the diameter is seen on an exaggerated scale to heighten its effect).

	The hydraulic simile
	Elements in the circuit
	Characteristic magnitudes
	Conclusions

	Ohm's law
	Power and energy in the circuit
	The generalization of the laws
	Conclusions

	The arrangement of resistances
	The arrangement of generators
	A combined circuit
	Conclusions