Question

correct answer only ​

Answer 1

Answer: 70 ohms

Explanation: L = PR = 30cm

                      RQ = 100 - PQ = 100 -L = 70 cm

                      r = 30 0hm

from meter bridge ,

PR / RQ = R /S

L / (100 - L ) = 30 / S

=> 30 / 70 = 30 / S

=> S = 70 ohms