Question

In the following potentiometer circuit, AB is a uniform wire of length 1 m and resistance 10 Ω. Calculate the potential gradient along the wire and balance length AO (= l).

 

Answer 1

Potential space gradient = `V_(AB)/I`

Using  Kirchhoff’s rules, 

`2=Ixx15+Ixx10=Ixx25=>I=2/25=0.08 A=>V_(AB)=Ixx10=0.8 =V`

`therefore " Potential space gradient "=(0.8/1)=0.8V/m`

Balance length = l

Potential difference across the balance length = Potential gradient × l

Potential difference across AO = 0.3 × 1 = 0.3 V

`therefore 0.3 V="Potential space gradient" xxI=>0.3=0.8xxI=>I=0.375 m=37.5`