a current carrying circular loop of radius R is placed in a uniform magnetic field B0 tesla in x-y plane as shown . The loop carries current i=1 A in direction shown. find torque acting on loop.
Answer is pi R^2 B0 / root 2 (i cap - j cap)

Please pass it on to friend Venkatesan
Hello Venkatesan, as per your observation
P/Q = 70/30 = 7/3 
Now P is having a parallel resistor with a value P/2. 
So effective will be P * P/2 / ( P + P/2) = P/3
Now let x cm be the null point
Then (P/3) / Q = x / 100 - x
But P/Q = 7/3
SO 7/9 = x /100 - x
Solving we get x = 43.75 cm nealy 43.8 cm
Thus the null point is shifted towards zero by 70 - 43.8 = 26.2 cm