The effective length of magnet is 31.4 cm and its pole strength is 0.8Am. The magnetic moment, if it is bent in the form of a semicircle is …….. A-m²

Options

(a) 1.2
(b) 1.6
(c) 0.16
(d) 0.12

Correct Answer:

0.16

Explanation:

The effective length of magnet = 31.4 cm

Pole strength, m = 0.8 Am

Length of semi-circle = π (D / 2) = l

where, D = diameter of circle

D = 2l / π = (2 × 31.4 × 10²) / 3.14 = 20 × 10⁻² m

Now, the magnetic moment = ml = mD = 0.8 × 20 × 10⁻² m

= 16 × 10⁻² = 0.16 A-m²