Three resistors with values R1, R2, and R3, respectively, are connected in parallel. Which of the following expresses the total resistance, RT, of the three resistors when connected in parallel?
1) RT = R1 + R2 + R3
2) RT = (1/R1 + 1/R2 + 1/R3)
3) RT = R1 = R2 = R3
4) RT = (1/R1 + 1/R2 + 1/R3)-1
5) RT = 3R1 = 3R2 = 3R3