# Ohms Law

Ohms Law

The relationship between current(I), voltage(V or E), and resistance(R) was discovered by a German scientist named Georg Ohm. This relationship is named Ohms Law in his honor. Ohm found that the current in a circuit varies directly with the voltage when the resistance is constant. Ohm varied the voltage across the resistance and measured the current through it. In each case, when he divided voltage by the current, the result was the same. In short, Ohms Law, which can be stated as, "The current is directly proportional to the voltage and inversly proportional to the resistance".

Written as a mathematical expression, Ohms Law is

Resistance(R)=voltage(V)/current(I) or R=V/I

The above equation allows you to determine the value of the resistance when the voltage and the current are known.

Of course, Ohms Law can be rearranged to solve for either current or voltage. The rearranged relationships are

current(I)=voltage(V)/resistance(R) or I=V/R

and

voltage(V)=current(I)*resistance(R) or V=IR

Here is a list of equations for power, voltage, current, and resistance

Power(W)= EI, I(squared)*R, E(squared)/R

Voltage(V)= IR, P/I, (sqrt)PR

Current(I)=E/R, P/E, (sqrt)P/R

Resistance(R)= E/I, E(squared)/P, P/I(squared)

Herbymcduff
1. jaimy skaria -
my everlasting doubt in current and voltage..
whether voltage can exist without current or vice versa???
can i take it ,voltage is the cause and current is its effect???please clear it..m in situation
of hating ma subjects..
1. parker -
i always imagine that Voltage is an ELECTRIC WATER PUMP (in HP) and water is the CURRENT, PIPE is CONDUCTOR cheers
1. MountainMike -
In dealing with Ohm's law, I hate rote memory, but yea, it is inevitable!

To simplify Ohm's law in my head, I always start off alphabetically;
"E" always comes before "I", which always comes before "R".

Thus, E = IR.

The remaining relationships can be easily worked out using Algebra.

I = E/R (divided both sides of the equation by "R")

R = E/I (divided both sides of the equation by "I")

And introducing "P" (power) into the equations;

P = IE (simple as apple "pie"!)

Substituting I = E/R, into the "P=IE" equation,

P = E/I x E = (E squared) divided by I.

... And all sorts of permutations of these two basic equations can be manipulated.
1. ssundar.shan -
Kindly include the word 'At Constant Temperature'. becoz depending upon temperature, the resistance may vary.....
Electronic Circuits  |  Learning Electronics

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