99 Percentile Qs Bank for JEE MainPhysicsMagnetic Effects of Current
Three long wires, with identical currents, either directly into or directly out of the page, are placed at three corners of a square in four different arrangements as shown. The correct order of the magnitude of the net magnetic field at the centre of the square is I II III IV
Options
- AB I = B I V > B I I = B I I I
- BB I I = B I I I = B I = B I V
- CB I = B I V < B I I = B I I I
- DB I > B I I I > B I I > B I V
Correct answer
C. B I = B I V < B I I = B I I I
Step-by-step solution
In figure I I and I I I field due to three wires add up. Hence, the magnitude is same. In figure I and I V field due to two wires cancel and the field is only due to third wire. ∴ B I =   B I   V   <   B I   I   =   B I   I   I