The effective length of magnet is 31.4 cm and its pole strength is 0.8Am.

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

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