A conducting disc 20 cm in diameter pivoted by a vertical spindle which is lying in uniform vertical magnetic field of flux density 0.3 T. A fixed brush is connected at the edge of the disc. When a 4 ohm resistance is connected across the brush and the spindle, a current of 15 mA was observed to flow through the resistor. Determine the velocity in which the disc is rotating.
Ampere Circuital Law
Ampere's Law states that "for any closed loop path, the sum of the length elements times the magnetic field in the direction of the length element is equal to the permeability times the electric current enclosed in the loop.”
Current Density
To design the electrical and electronic system, the current density is an important factor. The designer current level is the factor on which the circuit performance depends and with the help of the dimensions of the conducting current the current density is then determined. For instance, despite the lower current demanded by smaller devices as integrated circuits are reduced in size, there is a type of trend in achieving the higher device number in even smaller chip areas. The current density is increased in this region at higher frequencies because the conducting region in a wire becomes confined and this is known as the skin effect. The consequences increase as the current densities become higher.
A conducting disc 20 cm in diameter pivoted by a vertical spindle which is lying in uniform vertical magnetic field of flux density 0.3 T. A fixed brush is connected at the edge of the disc. When a 4 ohm resistance is connected across the brush and the spindle, a current of 15 mA was observed to flow through the resistor. Determine the velocity in which the disc is rotating.
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