Question

If a resistor Rx is connected between nodes X and Y, Ry between X and Y, Rz between Y and Z to form a delta connection, then after transformation to star, the resistance at node Y is?

(a) RzRy/(Rx+Ry+Rz)

(b) RzRx/(Rx+Ry+Rz)

(c) RxRy/(Rx+Ry+Rz)

(d) (Rz+Ry)/(Rx+Ry+Rz)

Answer 1

Correct choice is (b) RzRx/(Rx+Ry+Rz)

Explanation: After transformation to star, the resistor at node Y is RzRx/(Rx+Ry+Rz) and this resistance lies between Rx, Rz in star connection.