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5.Magnetism and Matter
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A tangent galvanometer has a coil of $100$ $turns$ and a radius of $20\,cm$. The horizontal component of the earth's magnetic field is $B_H = 3\times10^{-5}\,T$. Find the current which gives a deflection of $45^o$.
A
$0.082\, A$
B
$0.053\, A$
C
$0.091\, A$
D
$0.095\, A$
Solution
$\mathrm{i}=\mathrm{k}\, \tan\, \theta=\frac{2 \mathrm{rB}_{\mathrm{H}}}{\mu_{0} \mathrm{n}} \,\tan\, \theta$
$\frac{2 \times(0.20 \,\mathrm{m}) \times\left(3 \times 10^{-5}\, \mathrm{T}\right)}{4 \pi \times 10^{-7} \,\mathrm{TmA}^{-1} \times 100} \,\tan \,45^{\circ}=0.095 \,\mathrm{A}$
Standard 12
Physics
