In this article, we will discuss the formula of resistance in parallel connection. The resistances are connected in the series and parallel combinations to get the desired equivalent or total circuit resistance.
Formula for Parallel Circuit Resistance Calculations of the same Value Resistances
The equivalent resistance of the equal resistances connected in the parallel combination can be found by dividing the value of one resistance by the number of resistors.
The mathematical expression is;
Suppose four resistances of equal value(R) are connected in the parallel combination, the total resistance of the circuit is;
Example:
If 100 resistances, each resistance has a 400 Ohms value, are connected in the parallel combinations. What is the total resistance of the parallel circuit?
Formula for Parallel Circuit Resistance Calculations of the unequal Value Resistances
The total resistance of two resistances that have unequal resistance can be calculated in the following way.
Example:
The resistance value of the two resistances is 8Ω and 24Ω. These are connected in parallel. Calculate the total resistance of the circuit.
Finding Value of Unknown Resistance when two resistance connected in the parallel Circuit
We can find the value of unknown resistance when it is connected in parallel with a known value resistance.
- The value of total resistance is given
- The value of one resistance is known
Example:
Find the value of resistance to be added with 24Ω resistance to get a total resistance value of 16Ω when both the resistances are connected in the parallel.
| Note: The total or equivalent resistance of the parallel circuit is always less than the value of the resistance that has minimum resistance among all the resistances. If four resistances have resistance values 5,8,12,20 ohms and are connected in the parallel combination, then the total resistance of the circuit is always less than 5 ohms. |