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If sigma(1), sigma(2) and sigma(3) are t...

If `sigma_(1), sigma_(2)` and `sigma_(3)` are the conductances of three conductors, then their equivalent conductance, when they are joined in series, will be-

A

`sigma_(1) + sigma_(2) + sigma_(3)`

B

`1/sigma_(1) + 1/sigma_(2) + 1/sigma_(3)`

C

`(sigma_(1) sigma_(2) sigma_(3))/(sigma_(1) + sigma_(2) + sigma_(3))`

D

None of these

Text Solution

Verified by Experts

The correct Answer is:
D
`R_(eq) = R_(1) + R_(2) + R_(3) rArr 1/sigma_(1) + 1/sigma_(2) + 1/sigma_(3) = 1/sigma_(eq)`
`therefore sigma_(eq) = (sigma_(1) sigma_(2) sigma_(3)/(sigma_(2)sigma_(3) + sigma_(1)sigma_(3) + sigma_(1)sigma_(2)))`
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