Charge and Fields_1

Charge and Fields_1

1. Electric Fields

   • Acts radially (unless simplified model is being used)
   • Field strength equates to the potential gradient.
   • Field lines always go from positive potential to negative potential, as this is the direction in which a positively charged particle would feel a positive force (shown by arrow head)
   • Only affects charged particles

2. Gravitational Field

   • Force arising from 2 (or more) masses.
   • Forces act towards the centre of mass
   • Universal law of gravitation -GM1m2/r squared
   • Always acts radially (unless using the simplified model of the Earth)
   • Only affects massive particles (which is pretty much everything)

3. Magnetic Field

   • a magnetic field will induce a current in any conducting material.
   • Only affects charged particles
   • induced emf = -N x change in flux/change in time
   • when a mag. field induces a current, the current then induces a magnetic field to oppose the original. Lenz's law!
   • The force carrier for the electromagnetic force is the photon
   • Flux lines always emerge from a north pole and enter the south pole. They can never cross.
   • On a coil, the north face is the face in which the current is moving anticlockwise, and the south pole is the face at which it is moving clockwise

Images and files in the map