JEE Main 2025 Physics question
Consider a long straight wire of a circular cross-section (radius a) carrying a steady current I. The current is uniformly distributed across this cross-section. The distances from the centre of the wire's cross-section at which the magnetic field [inside the wire, outside the wire] is half of the maximum possible magnetic field, any where due to the wire, will be :
Answer: (2)
Solution
occurs at surface = . Half value inside at r=a/2, outside at r=2a.