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Figure alongside shows a uniform mangani...

Figure alongside shows a uniform manganin wire XY of length 100 cm and resistance `9Omega`, connected to an accumulator D of emf 4 V and internal resistance `1Omega` through a variable resistance R. E is a cell of emf 1.8 V connected to the wire XY via a jockey J and a central zero galvanometer G. It is found that the galvanometer shows no deflection when XJ = 80 cm. Find the value of R.

Text Solution

Verified by Experts

`E=Kl`
`1.8=Kxx0.80`
`K=2.25V//m=0.0225V//cm`
`K=(V)/(l)`
`0.0225=(V)/(100)`
`V=2.25" Volt"`
`V=IR`
`2.25=(4)/(10+R)xx9`
`10+R=(9xx4)/(2.25)`
`R=6Omega`
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