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Question:

Two circular loops having same radius R=10 cm and same current 72A are placed along same axis as shown. If distance between their centres is 10 cm, find net magnetic field at point P.

28μ05T

56μ05T

56μ03T

50μ05T

Solution:

Correct option is C. 56μ05T
At point P, magnetic field will be in same direction by both coils.
B=B1+B2 and B1=B2=μ0ir²/2(r²+n²)³/²
B=μ0ir²/2(r²+n²)³/² × 2
B=μ0ir²(r²+n²)³/²
B=μ0 × 72 × (0.1)²/[(0.1)²+(0.05)²]³/²=56μ05T.