Water-electronics analogy
Basic terms in electronics can be illustrated with water delivery system:
Water pipe = electric wire
Water flow = current flow
Water pump/tower = power supply
Water Sprinkler/tap = electric load

In order to deliver water in the pipe to the sprinkler, a water pump must push the water from one edge of the pipe to the other edge. As long as the water pipe is thinner, less water can flow in a time unit. This is exactly how the electronic circuit works, as long as the wire is thinner, less current can flow in a time unit. We will learn soon about a component in the electronic circuit called “resistor”, this component resist to part of the current flow through it. The analogy to “resistor” is a valve that adjusts the water flow in the pipe.

Ohm’s law
First and most important law in electronics is ohm’s law. This law is a formula that represents the relation between voltage, current and resistance as followed:

R = V/I

R = resistance
V = voltage
I = current

Playing with the formula can show another two representations:

I = V/R

V = I*R

We can see by ohm’s law that when resistance rises, the current is reduced. If we will measure the resistance of a resistor in the electronic circuit and the voltage between its two terminals we will be able to calculate the current that flow through the resistor with ohm’s law.

Resistor
Resistor is a component with constant and known resistance. The resistor includes two terminals that connect to the electric circuit. Resistors are manufactured on a large range of resistances as requested in each section of the electric circuit. The resistance of the resistor is defined during the manufacture process and usually marked on the resistor package with letters or color stripes code. The main function of the resistor in the electric circuit is to adjust currents and voltage in places where it is connected. Resistor in the electric circuit is marked with the letter R.

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