Q. Two thick wires and two thin wires, all of same material and same length, form a square in three different ways $P,\ Q\ and\ R$ as shown in the figure. With correct connections shown, the magnetic field due to the current flow, at the centre of the loop will be zero in case of
A) $Q\ and\ R$
B) $P\ only$
C) $P\ and\ Q$
D) $P\ and\ R$
Explanation
(d) In $P$ and $R,$ current divides equally in two halves because of equal resistances in the two halves. Due to equal currents in two halves the magnetic field at the centre will be zero.
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.