What are the application of ohm's law?

Answer 1

By using Ohm's law, you are able to find the resistance of a circuit, knowing only the voltage and the current in the circuit.

In any equation, if all the variables (parameters) are known except one, that unknown can be found. For example, using Ohm's law, if current (I) and voltage (E) are known, resistance (R) the only parameter not known, can be determined:

Basic formula:

Remove the divisor by multiplying both sides by R:

Result of step 2: R x I = E

To get R alone (on one side of the equation) divide both sides by I:

The basic formula, transposed for R, is:

Answer 2

Not many.

Ohm's Law is not a universal law, and applies in very few circumstances. In fact, it's a mystery why we still teach it in schools and colleges!

Ohm's Law states that 'the current in a conductor is directly-proportional to the potential difference across the ends of that conductor, provided all physical conditions, including temperature remain constant'. As the temperature of most metal conductors increase as the current passing through them increases, clearly Ohm's Law doesn't apply to most conductors.

Expressed another way, Ohm's Law only applies when the ratio of voltage to current is constant for variations in voltage. In other words, if we were to plot a graph of voltage to current, a straight line must result for Ohm's Law to apply. Varying the voltage across devices such as diodes results in a curve, which confirms Ohm's Law doesn't apply. Straight-line graphs result in so few circumstances.

However, the ratio of voltage (V) to current (I)is, by definition, resistance (R). So the equation, R = V/I, which is actually derived from the definition of the ohm and NOT (as many believe!) from Ohm's Law applies in all circumstances, but ONLY for a particular ratio of voltage to current. So we can apply this equation to any point along a curve, and it will tell us the resistance at each of those points.