A bar magnet when placed at an angle of 30° to the direction of magnetic field induction of 5 × 10-2 T, experiences a moment of couple 25 × 10-6 N m. If the length of the magnet is 5 cm, its pole strength is

Question

A bar magnet when placed at an angle of 30° to the direction of magnetic field induction of 5 × 10-2 T, experiences a moment of couple 25 × 10-6 N m. If the length of the magnet is 5 cm, its pole strength is (A) 2 × 10-2 A - m (B) 5 × 10-2 Am (C) 2 Am (D) 5 Am

Tardigrade Admin · Accepted Answer

τ=M B sin θ ⇒ τ=(m L) B sin θ ⇒ 25 × 10-6=(m × 5 × 10-2) × 5 × 10-2 × sin 30° ⇒ m=2 × 10-2 Am

Q. A bar magnet when placed at an angle of $3 0^{\circ}$ to the direction of magnetic field induction of $5 \times 1 0^{- 2} T$ , experiences a moment of couple $25 \times 1 0^{- 6} N m$ . If the length of the magnet is $5 c m$ , its pole strength is

$2 \times 1 0^{- 2} A - m$

$5 \times 1 0^{- 2} A m$

$2 A m$

$5 A m$

$τ = MB sin θ \Rightarrow τ = (m L) B sin θ$
$\Rightarrow 25 \times 1 0^{- 6} = (m \times 5 \times 1 0^{- 2}) \times 5 \times 1 0^{- 2} \times sin 3 0^{\circ}$
$\Rightarrow m = 2 \times 1 0^{- 2} A m$

Q. A bar magnet when placed at an angle of 30∘ to the direction of magnetic field induction of 5×10−2T, experiences a moment of couple 25×10−6Nm. If the length of the magnet is 5cm, its pole strength is

2×10−2A−m

5×10−2Am

2Am

5Am