A tangent galvanometer shows a deflection 45^o when 10 , mA curre… - Vidyadip

MCQ

A tangent galvanometer shows a deflection $45^o $ when $10\, mA$ current pass through it. If the horizontal component of the earth’s field is $3.6 \times {10^{ - 5}}\,T$ and radius of the coil is $10\, cm$. The number of turns in the coil is......$turns$

A
$5700$
B
$57$
✓
$570$
D
$5.7$

✓

Answer

Correct option: C.

$570$

c
(c) $K = \frac{{2r{B_H}}}{{{\mu _0}n}}$
or $n = \frac{{2r{B_H}}}{{{\mu _0}K}} = \frac{{2 \times 0.1 \times 3.6 \times {{10}^{ - 5}}}}{{4\pi \times {{10}^{ - 7}} \times 10 \times {{10}^{ - 3}}}}$ $ = \frac{{1.8 \times {{10}^3}}}{{3.14}} = 570$

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