How can the total equivalent resistance of three resistances in a series circuit be expressed?

In a series circuit, the total equivalent resistance can be calculated simply by adding together the individual resistances of the components connected in series. When resistors are arranged in this way, the total resistance is the sum of the individual resistances because the same current flows through each resistor one after the other.

So, for three resistors R1, R2, and R3 connected in series, the total equivalent resistance, denoted as R_total, is expressed mathematically as:

R_total = R1 + R2 + R3.

This relationship is fundamental in circuit theory and reflects the principle that when resistors are added in series, their resistances accumulate, leading to a higher total resistance. The other options describe different arrangements of resistances, such as parallel configurations or averaging, which do not apply to series circuits.