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BIOT
SAVART LAW
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Consider a long straight conductor carrying current I. Then magnetic field is in the form of circle. BIOT SAVART found that the magnitude of field B is directly proportional to twice of current I and inversely proportional to the distance r. |
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B a 2I And B a 2I/r B = mo/4p.2I/r |
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is called permeability of free space. mo/4p is proportionality constant. Its value is 10-7. |
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AMPERE’S
LAW
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STATEMENT: This law states: "The sum of products of tangential component of B and length element Dl of a closed curve is mo times the current enclosed." mo = permeability of free space. Its value is 4p*10-7. Its unit is Henry/m2. Mathematically. |
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S(B.Dl)
= moI
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PROOF
OF AMPERE’S LAW
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Let the circular field B be divided in to small elements Dl. Now tangential component of B |
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Bx = BCosq
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| Multiplying length element Dl with tangential component of B, we have, | |||
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B. Dl = BCosq. Dl But, q is negligible i.e. q = 0 B. Dl = BCos(0o). Dl B. Dl = B (1) . Dl B. Dl = B. Dl |
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| For the complete curve, the sum of their products will be, | |||
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SB. Dl = SB. Dl = BS. Dl but, B = mo/4p.2I/r and SDl = 2pr SB.Dl = mo/4p.2I/r x 2pr SB.Dl = mo x I |
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| This is mathematical form of Ampere’s law. | |||
| For latest information , free computer courses and high impact notes visit : www.citycollegiate.com | |||