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Question:

A symmetric star-shaped conducting wire loop is carrying a steady-state current I as shown in the figure. The distance between the diametrically opposite vertices of the star is 4a. The magnitude of the magnetic field at the center of the loop is

µ₀I/(4πa⁶)[√3+1]

µ₀I/(4πa³)[2−√3]

µ₀I/(4πa³)[√3]

µ₀I/(4πa⁶)[√3]

Solution:

B=µ₀I/(4πa)(sin60°−sin30°)=µ₀I/(4πa)[√3/2−1/2]
B=µ₀I/(4πa)×6[√3/2]
Hence correct answer is A.