Explanation

The formula to calculate the total resistance (Rt) of two resistors, R1 and R2, connected in parallel in an electric circuit is:

1/Rt = 1/R1 + 1/R2

This formula is based on the principle that the total resistance in a parallel circuit is the reciprocal of the sum of the reciprocals of the individual resistances.

To understand how this formula works, consider the following example:

Let's say you have two resistors, R1 = 10 ohms and R2 = 20 ohms, connected in parallel. To find the total resistance of the circuit, you would substitute the values of R1 and R2 into the formula like this:

1/Rt = 1/10 + 1/20

By solving this equation, we get the total resistance in the circuit:

1/Rt = 1/10 + 1/20 Rt = 2/ (1/10 + 1/20) = 2/(1/10 + 1/20) = 2/(1/10 + 1/20) = 2/ (3/20) = 40/3 = 13.33 ohms