The distance between the poles of horse shoe magnet is 10 cm and its pole strength is 104 A. The magnetic field induction at point P mid-way between the poles is :

Question

The distance between the poles of horse shoe magnet is 10 cm and its pole strength is 104 A. The magnetic field induction at point P mid-way between the poles is : (A)  8× 10-9 tesla (B)  4× 10-19 tesla (C)  2× 10-9 tesla (D) zero

Tardigrade Admin · Accepted Answer

B=B1+B2=(μ0/4 π)((m1/r12)+(m2/r22)) as m1=m2 and r1=r2 so, B =(μ0/4 π) (2 m1/r12) =10-7 (2 × 10-4/(5 × 10-2)2) =8 × 10-9 T

Q. The distance between the poles of horse shoe magnet is $10 c m$ and its pole strength is $1 0^{4}$ A. The magnetic field induction at point $P$ mid-way between the poles is :

$8 \times 1 0^{- 9}$ tesla

$4 \times 1 0^{- 19}$ tesla

$2 \times 1 0^{- 9}$ tesla

zero

$B = B_{1} + B_{2} = \frac{μ _{0}}{4 π} (\frac{m _{1}}{r _{1}^{2}} + \frac{m _{2}}{r _{2}^{2}})$
as $m_{1} = m_{2}$ and $r_{1} = r_{2}$
so, $B = \frac{μ _{0}}{4 π} \frac{2 m _{1}}{r _{1}^{2}}$
$= 1 0^{- 7} \frac{2 \times 1 0 ^{- 4}}{( 5 \times 1 0 ^{- 2} ) ^{2}}$
$= 8 \times 1 0^{- 9} T$

Q. The distance between the poles of horse shoe magnet is 10cm and its pole strength is 104 A. The magnetic field induction at point P mid-way between the poles is :

8×10−9 tesla

4×10−19 tesla

2×10−9 tesla