Question

Write an expression for the magnetic field produced by an
infinitely long straight wire carrying a
current I, at a short perpendicular distance a from itself.
please give explanation​

Answer 1

Answer:

Ampere's law equation  

∮  B  .  dℓ =μ∑i

Here  

B.  ℓ =μ∑i

here  

dμ  length  element perpendicular to the plane of paper  

∮  B .  dℓ =μ  o ∑i

B → magnetic field which is also perpendicular to plane of paper & align with length elements  

∮  B  .  dℓ =μ  o ∑i

B.∮dℓ=μ  o i

B.2π=μ  o i

B=  2πr μ  o i

​