PHYSICS · Multi-part · CBSE · Physics · Moving Charges and Magnetism · Moving Charges and Magnetism
Problem
Two coplanar circular loops, loop A of radius 5cm and loop B of radius 12cm, have their centres on the same axis and lie in the same plane. Both loops carry steady currents but in opposite senses: loop A carries 4A clockwise and loop B carries 9A anticlockwise when viewed from the same side.
(i) Derive an expression for the magnetic field at a point on the common axis at a distance x from the centre of a single circular loop of radius R carrying current I.
(ii) Using the result of part (i), obtain an equation that must be satisfied by x so that the net axial magnetic field due to the two loops is zero on the side of loop A.
(iii) Solve the equation of part (ii) to find the numerical value of x.
(iv) Comment on whether any point with zero net field can exist on the side of loop B and justify your answer.