Question

In a unbalanced wheatstone bridge the potential between the galvanometer is not

zero. If the galvanometer resistance is 20Ω, what is the galvanometer current? Lets

take Voltage = 20V , P/Q ratio as 4, known resistance as 6Ω and unknown resistance

as 3Ω.​

Answer 1

The balanced condition for Wheatstones bridge is  

Q

P

​  

=  

S

R

​  

 

as is obvious from the given values.

No, current flows through galvanometer is zero.

Now, P and R are in series, so

Resistance,R  

1

​  

=P+R

=10+15=25Ω

Similarly, Q and S are in series, so

Resistance R  

2

​  

=R+S

=20+30=50Ω

Net resistance of the network as R  

1

​  

 and R  

2

​  

 are in parallel

i=  

R

V

​  

=  

50

6×3

​  

=0.36 A.