Question

Two infinitely long current carrying conductors X and Y are kept parallel to each other, 24 cm apart in a vacuum. They carry currents of 5A and 7A respectively, in the same direction, as shown in the figure below. Find the position of a neutral point, i.e., a point where resultant magnetic flux density is zero. (Ignore earth’s magnetic field). 

Answer 1

B = `(mu_0"I" xx 2)/(4pi xx 10^-2) [5/"X" - 7/(24 - "X")] = 0` [At neutral point B = 0]

`therefore 5/"X" = 7/(24 - "X")`

12X = 120

X = 10 cm

∴ The position of null point will be at 10 cm from ‘X’ wire.