Two circular loops having same radius [ R = 10 cm] and same current `(7)/(2)A` are placed along same axis as shown. If distance between their centre is 10 cm. find net magnetic field at of point P.

Options

A. `(50mu_(0))/(sqrt5)T`
B. `(28mu_(0))/(sqrt5)T`
C. `(56mu_(0))/(sqrt5)T`
D. `(56mu_(0))/(sqrt3)T`

Answer

C

Explanation

At point P, magnetic field will be in same direction by both coils.
`B=B_(1)+B_(2)" and "B_(1)=B_(2)`
`B=(mu_(0)ir^(2))/(2(r^(2)+n^(2))^(3//2))xx2`
`B=(mu_(0)ir^(2))/((r^(2)+n^(2))^(3//2))`
`B=(mu_(0)xx(7)/(2)xx(.1)^(2))/([(0.1)^(2)+(0.05)^(2)]^(3//2))=(56mu_(0))/(sqrt5)T`