Question

Two long parallel straight wires, each carrying a current I are separated by a distance r. If the currents are in opposite directions, then the strength of the magnetic field at any point midway between the two wires is

• A.
  
• B.
  
• C.
  
• D. Zero

Answer 1

The correct option is B

$B_1=\frac{{\mu }_{0}I}{2\pi \left(\frac{r}{2}\right)}\oplus B_2=\frac{{\mu }_{0}I}{2\pi \left(\frac{r}{2}\right)}\oplus \Rightarrow B=\frac{2{\mu }_{0}I}{\pi r}\oplus$