This preview shows page 1. Sign up to view the full content.
Unformatted text preview: Y ? (c) The gap between plates X and Y is then filled completely with a material of resistivity η , 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 − 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 ω . 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 − + + = + ∫ ]...
View Full Document
This note was uploaded on 10/14/2010 for the course PHYS 2051 taught by Professor Drkwong during the Spring '10 term at CUHK.
- Spring '10