Time period of magnet in vibration magnetometer, T=2π√‌
I
MH
First case, T1=2π√‌
I1+I2
M′H
where, M= resultant magnetic moment of two magnets Here, two identical magnets are placed perpendicular to each other. ‌∴‌‌I1=I2=I‌ (Let) ‌ ‌‌ and ‌‌‌M′=√M2+M2=M√2 ‌∴‌‌T1=2π√‌
2I
√2MH
‌25∕4=2π√‌
2I
√2MH
. . . (i) When one magnet is removed, then time period, T2=2π√‌
I
MH
. . . (ii) On dividing Eq. (i) by Eq. (ii), we get ‌