Unformatted text preview: Y ? (c) The gap between plates X and Y is then filled completely with a material of resistivity Î· , so that a current I flows from Y to X with a uniform current density. Draw an equivalent RC circuit for the system, and hence find the initial current and the time for the current to drop to 1 âˆ’ e of the initial value (Neglect dielectric effect). Fig. 1 3. A non-conducting circular disc of radius R has a total charge +q uniformly distributed over its surface. The disc rotates about its axis at a constant angular velocity Ï‰ . Starting from Biot-Savart law, derive an expression for the magnetic field produced by the disc along its axis. In particular, what is the magnetic field at the centre of the disc? [ Hint : ( ) z z R z R dr z r r R 2 2 2 2 2 2 2 3 2 2 3 âˆ’ + + = + âˆ« ]...
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- Spring '10
- Charge, Magnetic Field, Electric charge, total charge, surface charge density, STOT Problem Set