A cell in secondary circuit gives null deflection for 2.5 ~m length of potentiometer having 10 ~m length of wire. If the length of the potentiometer wire is increased by 1 ~m without changing the cell in the primary, the position of the null point now is

Step-by-step solution

Resistance of potentiometer wire R= l A or R= ( 10 A ) The value of 2.5 ~m length wire R^ = 10 A 10 2.5 or R^ = ( 2.5 A 10 ) Potential aligned V^ & =I R^ & =I ( 2.5 A 10 ) aligned Now, again the length of potentiometer wire is increased by 1 ~m , then resistance of null position wire. aligned R^ & = ( l 11 A ) V^ & =I R^ and V & =V^ aligned aligned I 2.5 A 10 & = l 11 A I or 2.5 11 10 & =l=2.75 ~m aligned