Question

Two circular loops having same radius [R = 10 cm] and same current $\frac{7}{4}$ Aare placed along same axis as shown. If distance between their centre is 10 cm, find net magnetic field at of point P.

• A. $\frac{50{\mu }_0}{\sqrt{5}}$ T
• B. $\frac{28{\mu }_0}{\sqrt{5}}$ T
• C. $\frac{56{\mu }_0}{\sqrt{5}}$ T
• D. $\frac{56{\mu }_0}{\sqrt{3}}$ T

Answer 1

Answer: (C)

At point P, magnetic field will be in same direction by both coils.
B = B₁ + B₂ and B₁ = B₂
$B=\frac{{\mu }_{0}i{r}^2}{2{\left(r^2+n^2\right)}^{\frac{3}{2}}}\times 2$
$B=\frac{{\mu }_{0}i{r}^2}{{\left(r^2+n^2\right)}^{\frac{3}{2}}}$
$B=\frac{{\mu }_0\times \frac{7}{2}\times {\left(0.1\right)}^2}{{\left[{\left(0.1\right)}^2+{\left(0.05\right)}^2\right]}^{\frac{3}{2}}}=\frac{56{\mu }_0}{\sqrt{5}}T$