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In a metre bridge when the resistance in the left gap is 2Omega and an unknown resistance in the right gap, the balance point is obtained at 40 cm from zero end. On shunting the unknown resistance with 2Omega, find the shift of the balance point on the bridge. |
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Answer» Solution :The unknown resistance (S)is on the RIGHT gap, So at null point, `S = R (100 - l)/(l) = 2 xx (100 - 40)/(40) = 3Omega` When S is shunted with 2`Omega`, the resistance on the right gap is, `S' = (3 xx 2)/(3 + 2 ) = 1.2Omega` If balance is obtained at a DISTANCE l', then `S' = R(100 - l')/(l') = R((100)/(l') - 1)` or, `"" l' = (100R)/(R + S') = (100 xx 2)/(2 + 1.2) = 62. 5 cm` `therefore` Shift in balance point= 62.5 - 40 = 22.5 cm |
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