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Question: Moment of inertia of a magnetic needle is 40 gm-cm<sup>2</sup> has time period 3 seconds in earth's ...

Moment of inertia of a magnetic needle is 40 gm-cm2 has time period 3 seconds in earth's horizontal field = 3.6×10−53.6 \times 10 ^ { - 5 }weber/m2. Its magnetic moment will be

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Answer

Explanation

Solution

T=2πIMBHT = 2 \pi \sqrt { \frac { I } { M B _ { H } } }

I=40gm−cm2=400×10−8 kg−m2I = 40 \mathrm { gm } - \mathrm { cm } ^ { 2 } = 400 \times 10 ^ { - 8 } \mathrm {~kg} - \mathrm { m } ^ { 2 }

∴3=2π400×10−836×10−6×M\therefore 3 = 2 \pi \sqrt { \frac { 400 \times 10 ^ { - 8 } } { 36 \times 10 ^ { - 6 } \times M } }