\(\mathrm{n}=1000\) \(turns/\)\(\mathrm{cm}=1000 \times 100\) \(turns\) \(/ \mathrm{m}\)
Coercivity of ferromagnet. \(\mathrm{H}=100 \,\mathrm{A} / \mathrm{m}\)
Current to demagnetise the ferromagnet, \(I=?\)
Using, \(H=n I\)
or, \(\quad 100=10^{5} \times I\)
\(\therefore \mathrm{I}=\frac{100}{10^{5}}=1\, \mathrm{mA}\)
($\frac{{{\mu _0}}}{{4\pi }}\, = 10^{- 7}$ $SI$ એકમમાં અને $B_H\, =$ ચુંબકીય ક્ષેત્રનો સમક્ષિતિજ ઘટક $= 3.6\times10^{-5}\, tesla$)