# While solving questions based on electricity, how will we determine the correct direction for calculating the resistance if there are many resistors?

justaguide | Certified Educator

Resistors are components that have a linear change in current flowing through them when the voltage applied across them is changed. The flow of current through a resistor is possible in both directions and the magnitude remains the same irrespective of which direction the voltage is applied in.

In a circuit with many resistors, all the resistors are configured such that some of them are in series and some of them are in parallel.

For two resistors, R1 and R2, that are in series, the equivalent resistance is equal to R where R = R1 + R2. If the resistors R1 and R2 are in parallel, the equivalent resistance R is given by 1/R = 1/R1 + 1/R2.

To determine the equivalent resistance when there are many resistors in a circuit, the resistors should be grouped as sets of resistors that are in series and which of these sets are in parallel. Using the formula for equivalent resistance provided earlier, the equivalent resistance of each set can be determined and this can then be used to determine the equivalent resistance of the entire circuit.

As resistors behave in the same way irrespective of which direction current is flowing in and the direction the voltage has been applied across the resistor, there is no correct direction as far as finding equivalent resistance is concerned.