Question

A long straight wire in the horizontal plane carries a current of 50A in north to south direction. Find the magnitude and direction of B at a point 2.5m east of the wire.

Answer 1

Formula used: B=μ0I/2πr.

As we already know that for an infinite conductor, the magnetic field B at a perpendicular distance r is equal to-

⇒ B=μ0I/2πr.

 

As we know that, μ0 is equal to 4π×10−7. We will substitute this value into the equation above as well as the values of current I, and the value of radius-

Current I as per given in the question = 50A

Radius r as per given in the question = 2.5m

Thus, we will have-

 

⇒ B=μ0I/2πr

⇒ B = 4π×10−⁷ × 50/2π×2.5

⇒ B = 2×10−⁷ × 500/25

⇒ B = 4×10−⁶T

 

Now, we know that the magnetic field has a value of 4×10−⁶T.

 

 

Magnitude and direction of B at point 2.5 east of the wire = 4×10-⁶ T