To study variation of magnetic field with distance on the axis of a circular coil carrying current
Stewart Gee type galvanometer, battery plug key, commutator, rheostat and ammeter.
Stewart and Gee galvanometer is shown above. Its construction resembles that of tangent galvanometer and deflection magnetometer. It consists of a circular coil in a vertical plane fixed to a horizontal bench at its middle point. The ends of the coil are connected to binding screws. A magnetic compass box is arranged such that it can be sided along a horizontal scale passing through the center of the coil. The length of the scale is perpendicular to the plane of the coil. The compass box consists of a short magnetic needle and a long aluminum pointer attached at its midpoint perpendicular to it and they are pivoted at the center of a horizontal circular scale graduated in diagrams. The circular scale consists of four quadrants each of which measures angles from 0 degree to 90 degree. A plane mirror is provided below the pointer so that the deflections can be provided without parallax.
Formula:The magnetic field B at a point on the axis of a circular coil of a turns and radius a is given by the equation
B =μ0nia^{2}/2(x ^{2}+ α ^{2}) ^{3/2}
Where I = current passing through the coil
X = distance of the point from the center of the coil.
BH = 0.38x10 ^{-4}Tesla
μ0 = 4πX10 ^{7}
Current I =----------amp.
n= …..
S.No | Positio n magnet o main | Distance x | Deflection/θ1/θ2/θ3/θ4/ | Average θ | Tan θ | B = B _{H}tan θ | B= |
1 | Left (-)West of the coil | ||||||
2 | Right (+) East of the coil |
The values of F calculated from equation B = B _{H}tan θ and should be equal.
B =μ0nia^{2}/2(x ^{2}+ α ^{2}) ^{3/2}
As B α tan θ, B vs. graph resembles tan θvs. x graph. The graph of Tan B = B _{H}tan θ vs. x is shown below
The variation of magnetic field with distance on the axis of a circular coil carrying current is verified.
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