An electron (charge `q=1.6xx10^(-19)C)` in the potentiometer wire experiences a force of `2.4xx10^(-19)`N. The length of the potentiometer wire is 6 m. The e.m.f. of the battery connected across the wire is

Options

A. 12 V
B. 9 V
C. 6 V
D. 3 V

Answer

B

Explanation

`E=(F)/(q) and E=(dv)/(dx) " " therefore (dv)/(dx)=(F)/(q)`
`therefore dv= (Fdx)/(q)= (F l)/(e )=(2.4xx10^(-19)xx6)/(1.6xx10^(-19))=9 V`
`therefore E= 9 V`