The distance of two points on the axis of a magnet from its centre is `10 cm` and `20 cm` repectively. The ratio of magnatic intensity at these points is `12.5 : 1`. The length of the megnet will beA. 5cmB. 25cmC. 10cmD. 20cm

The distance of two points on the axis of a magnet from its centre is

1.	The distance of two points on the axis of a magnet from its centre is `10 cm` and `20 cm` repectively. The ratio of magnatic intensity at these points is `12.5 : 1`. The length of the megnet will beA. 5cmB. 25cmC. 10cmD. 20cm
Answer» Correct Answer - C `B_(1)/B_(2)=d_(1)/d_(2)((d_(2)^(2)-l^(2))/(d_(2)^(1)-l^(2)))^(2) rArr 12.5/1=10/20((400-l^(2))/(100-l^(2)))^(2)` `rArr l=5 cm` Hence, length of magnet `=2l=10 cm`

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The distance of two points on the axis of a magnet from its centre is `10 cm` and `20 cm` repectively. The ratio of magnatic intensity at these points is `12.5 : 1`. The length of the megnet will beA. 5cmB. 25cmC. 10cmD. 20cm

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