Ohm's Law

From TheBestCaseScenario

[edit] Ohm's Law

Ohms law describes the fundamental relationship between the three most important measurements in electronics, Voltage (E), Current (I) and Resistance (R). This relationship was discovered by a german chap named Georg Ohm. He first published Ohms law in 1827 in a book named "Electricity". The law itself is probably the most important law for those designing elctronic circuits. With it you can calculate the value of either voltage, current or resistance if you know the values of the other two.

[edit] The Law

Ohms law is defined as "Voltage(volts) is equal to the product of the current(amps) flowing through a resistance(ohm) within a circuit.

To put that another way Voltage(E)=Current(I) X Restance(R)or...

E=IR

This can be reaaranged to

I=E/R

to calculate current or

R=E/I

To calculate resistance.

[edit] Examples

In the following cicuit (fig 1) You can see a resistor(see resistors) attached to a battery. The current flows from the negative terminal of the battery and through a resistor

If we know that the Resistor has a value of 200ohm, and the current is 0.06amps what is the voltage of the circuit?

Well

E=IR

E=0.06a x 200ohm

E=12v

In the same circuit if we know that the resistor has a value of 100ohm, and the battery has a voltage of 1.5v we can calculate the current to be...

I=E/R

I=1.5v/100ohm

I=0.015amps

This is very useful to know as most electrical components are rated to a maximum amp and volts. With Ohms law you can calculate the maximum ratings that you will need in order to make sure your components are not overloaded.

--justblair 10:36, 22 September 2006 (EDT)