Question

If the resistors of star connected system are R1, R2, R3 then the resistance between 1 and 2 in delta connected system will be?

(a) (R1R2 + R2R3 + R3R1)/R3

(b) (R1R2 + R2R3 + R3R1)/R1

(c) (R1R2 + R2R3 + R3R1)/R2

(d) (R1R2 + R2R3 + R3R1)/(R1+R2)

The question was posed to me by my college professor while I was bunking the class.

I'm obligated to ask this question of Star-Delta Transformation topic in section Useful Theorems in Circuit Analysis of Network Theory

Answer 1

Correct option is (a) (R1R2 + R2R3 + R3R1)/R3

To explain: After transformation to delta, the resistance between 1 and 2 in delta connected system will be (R1R2 + R2R3 + R3R1)/R3 and this resistance lies between R1, R2 in delta connection.