Question

Two imaginary isolated North poles of pole strength
0.4 Am and 6.4 Am are separated by 10 cm. Dis-
tance of neutral point from 0.4 Am is
(1)
2 cm
(2)
4 cm
(3) 8 cm
10 cm​

Answer 1

Step-by-step explanation:

hope this answer is helpful

Answer 2

Answer:

The distance of neutral point from 0.4 Am is 2cm.

Step-by-step explanation:

Given the pole strengths, $m_{1} =0.4 Am$ and $m_{1} =6.4 Am$

Distance between the poles, $d= 10 cm=0.1m$

Let the distance of neutral point from 0.4 Am be $r$.

The magnetic field due to an isolated pole at distance r is

$B=\frac{\mu_{0} }{4\pi } \frac{m}{r^{2} }$

A neutral point is a point where the resultant magnetic field from the sources is zero, therefore $B_{1} =B_{2}$

$\implies \frac{\mu_{0} }{4\pi } \frac{m_{1} }{r^{2} }=\frac{\mu_{0} }{4\pi } \frac{m_{2} }{r^{2} }$

$\implies \frac{0.4 }{r^{2} }= \frac{6.4 }{(0.1-r)^{2} }$

$\implies \frac{(0.1-r)^{2} }{r^{2} }= \frac{6.4 }{ 0.4}$

Taking square root on both sides,

$\implies \sqrt{\big(\frac{0.1-r}{r} \big)^{2}} =\sqrt{16}$

$\implies\frac{0.1-r}{r} =4$

$\implies 0.1-r=4r$

$\implies 5r=0.1\implies r=\frac{0.1}{5} =0.02m$

Therefore, the distance of neutral point from 0.4 Am is 0.02m or 2cm.

Hence, the correct answer is option (1).