Mathematics
Mathematics
Problem
Two long parallel wires P and Q are 6 cm apart, with P lying to the east of Q. Both wires run along the north–south line. Wire P carries 8 A towards north, while wire Q carries 4 A towards north. Point R is exactly midway between the wires. The net magnetic field at R is directed a) vertically downward b) vertically upward c) zero (fields cancel) d) towards EastIntuitive explanation
The key is superposition of magnetic fields from two current-carrying wires. Use the right-hand rule to find each wire's field direction at point R, then add them as vectors. Since the wires carry current in the same direction (north) but have different magnitudes, their magnetic fields at R won't cancel—you need to determine which dominates and in what direction the net field points.
Intuitive explanation
The key is superposition of magnetic fields from two current-carrying wires. Use the right-hand rule to find each wire's field direction at point R, then add them as vectors. Since the wires carry current in the same direction (north) but have different magnitudes, their magnetic fields at R won't cancel—you need to determine which dominates and in what direction the net field points.