A bar magnet has total length 2 l = 20 units and the field point P is at a distance d = 10 units from the centre of the magnet. If the relative uncertainty of length measurement is 1% , then uncertain

Question

A bar magnet has total length 2 l = 20 units and the field point P is at a distance d = 10 units from the centre of the magnet. If the relative uncertainty of length measurement is 1% , then uncertainty of the magnetic field at point P is :

TestHub · Accepted Answer

Magnetic field at P , B = 4 π μ 0 ​ ​ r 3 m ( 2 l ) ​ , where m is the pole strength ⇒ ( B Δ B ​ × 100 ) ​ = ( l Δ l ​ ) × 100 + 3 ​ r Δ r ​ ​ × 100 = 1% + 3% = 4% ​

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