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A bar magnet has length 3 cm, cross-sectional area `2 cm^(3)` and magnetic moment `3 Am^(2)`. The intensity of magnetisation of bar magnet isA. `3 xx 10^(5) A//m`B. `4xx 10^(5) A//m`C. `2 xx 10^(5) A//m`D. `1 xx 10^(5) A//m` |
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Answer» Correct Answer - D Given `l = 5 cm = 5 xx 10^(-2)m`, `a = 2 cm^(2) = 2 xx 10^(-4) m^(-2)` `a = 2 cm^(2) = 2 xx 10^(-4) m^(2)` and `M = 1 Am^(-2) ` The magnetisation of the bar magnet is given by `I =(M)/(V)` where V = volume of bar magnet `= a xx l` `rArr " " i = (M)/(a xx l)` Substituinting given values , we get `I =(1)/(2xx 10^(-4) xx 5 xx 10^(-2)) =(1)/(10^(-5))` ` = 1xx 10^(5) A//m` |
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