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In a meter bridge, the wire of length...

In a meter bridge, the wire of length 1 m has a non- uniform cross - section such that , the variation `(dR)/(dl)` of its resistance R with length l is `(dR)/(dl) prop (1)/(sqrt(l))` ,Two equal resistances are connected as shown in the figure , the galvanometer has zero deflection when the jockey is at point P, what is the length Ap?

A

0.2 m

B

0.3 m

C

0.25 m

D

0.35m

Text Solution

Verified by Experts

The correct Answer is:
C
`dR = (cdl)/sqrt(l)`
According to Question-
`int_(0)^(l)c(dl)/sqrt(l) = int_(l)^(1) c(dl)/sqrt(l)`
`(2sqrt(l))_(0)^(1) =(2sqrt(l))_(l)^(1) rArr 2sqrt(l) =2-2sqrt(l)`
`4sqrt(l) = 2 rArr I =1/4 = 0.25 m`
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