A Wheatstone bride is almost balanced with point `C` grounded. Calculate (a) the potential of point `B` (b) the potential of point `D` (c) If a galvanometer is connected between B and D, what is the direction of current through it ? (d) For what value of the resistance `BC` would the bridge be in balanced state ?

Answer

`22 Omnega`

Explanation

(a) curr ent through arm `ABC`
`l = 4 8//(10 + 20) = 1.6 A `
pot diff across `B and C = V_(B) - V_(C) = 1.6 xx 20 = 32 V`
As `V_(C) = 0 so V_(B) = + 32 V`
(b) current through arm `ADC`
`I' = 48//(5 + 11) = 3A`
pot diff across `D and C = V_(p) - V_(C) + 3 xx 11 = 33`
or `V_(D) gt V_(C) ` so direction of current will be `D to B`
(d) The bridge will be balance where
`(10)/(R ) = (5)/(11) or R = (10 xx 11)/(5) = 22 Omnega`