The couple acting on a magnet of length 10 cm and pole strength 15 Am, kept in a field of B=2 × 10-5 T, at an angle of 30° is

Question

The couple acting on a magnet of length 10 cm and pole strength 15 Am, kept in a field of B=2 × 10-5 T, at an angle of 30° is (A)  1.5× 10-5Nm  (B)  1.5×10-3Nm  (C)  1.5×10-2Nm  (D)  1.5×10-6Nm

Tardigrade Admin · Accepted Answer

C = MB sin θ =( m × 21) × 2 × 10-5 sin 30° =150 × 10-2 × 2 × 10-5 × (1/2)=1.5 × 10-5 N - m

Q. The couple acting on a magnet of length $10 c m$ and pole strength $15 A m$ , kept in a field of $B = 2 \times 1 0^{- 5} T$ , at an angle of $3 0^{\circ}$ is

$1.5 \times 1 0^{- 5} N m$

$1.5 \times 1 0^{- 3} N m$

$1.5 \times 1 0^{- 2} N m$

$1.5 \times 1 0^{- 6} N m$

$C = MB sin θ$
$= (m \times 21) \times 2 \times 1 0^{- 5} sin 3 0^{\circ}$
$= 150 \times 1 0^{- 2} \times 2 \times 1 0^{- 5} \times \frac{1}{2} = 1.5 \times 1 0^{- 5} N - m$

Q. The couple acting on a magnet of length 10cm and pole strength 15Am, kept in a field of B=2×10−5T, at an angle of 30∘ is

1.5×10−5Nm

1.5×10−3Nm

1.5×10−2Nm

1.5×10−6Nm