Two long conductors 10 cm apart carry currents in the ratio 1 :2 in the same direction. The magnetic field midway between them is 2 ×  10−3 T The force on unit length of any one conductor will be

Magnetic field at their mid-point,B=μ02πd2  2i−i  = μ0iπdGiven  μ0iπd  =  2 ×  10−3 TSubstituting d = 0.1 m, we get i=1032 AMagnetic field at the location of second conductor due to first conductor is, B=μ0i2πdForce on unit length of second conductor=B×  2i=μ0i2πd =  μ0iπd × i =  1N