In a potentiometer arrangement, a cell of emf 1.20 volt gives a balance point at 30 cm length of the wire. This cell is now replaced by another cell of unknown emf. If the ratio of the emfs of the two cells is 1.5, calculate the difference in the balancing length of the potentiometer wire in the two cases. 

Explanation

`(E_(1))/(E_(2))=1.5`
`E_(1)=1.2V`
`L_(1)=30Cm`
`L_(2)=`?
`(E_(1))/(E_(2))=(L_(1))/(L_(2))`
`(L_(2))/(L_(1))=(1)/(1.5)`
`L_(2)=(1)/(1.5)xx30`
`L_(2)=(cancel30^(2))/(cancel15)xx10`
`L_(2)=20Cm`
Now difference in the balancing length of potentiometer wire .
`=30-20=10`
`=10Cm`