defence exam Agniveer Vayu Group X & XY Mock Test 01/2026 Physics Moving Charges and Magnetism Magnetic Force on a Current-Carrying Wire
A long straight wire with a circular cross-section having radius R, is carrying a steady current I. The current I is uniformly distributed across this cross-section. Then the variation of magnetic field due to current I with distance r(r < R) from its centre will be :
1
B ∝ r2
2
B ∝ r
3
B ∝ \(\frac{1}{r^{2}}\)
4
B ∝ \(\frac{1}{r}\)