Charged particle above fixed oppositely charged ring
\n",
"\n",
"If the particle is placed, on axis, a distance z above the centre of the ring and released, the force on the particle can be found by integrating around the ring.\n",
"\n",
"
\n",
"\n",
"In the case that z << r, the radius of the ring, then the force is approximately proportional the displacement. Hence SHM will occur. Otherwise the motion produced is non-trivial, especially if the particle is placed off-axis. The on-axis result:\n",
"\n",
"
\n",
"\n",
"Using the above, it can be noted that for 2 fixed particles the linear restoring force occurs at all angles normal to the line connecting them. A charged particle in this plane, close to the midpoint, will then be capable of circular motion about the midpoint. However as the distance to the midpoint increases, z is not longer << r and the force no longer proportional to z, this will mean that the orbits will no longer close.\n",
"\n",
"Importing numpy along with charge_module which contains the Animation class created for this notebook along with plotter for the electric field on-axis. Using %matplotlib notebook allows interactive plots and animations within the notebook"
]
},
{
"cell_type": "code",
"execution_count": 1,
"metadata": {
"collapsed": false
},
"outputs": [],
"source": [
"import numpy as np\n",
"import charge_module as cm\n",
"\n",
"%matplotlib notebook"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"Time stepping of the particle position is done via a 4th order RK method"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"The acceleration caused by the charged ring (which is modelled as point particle sections as a approximation to the integration required) for a unit mass:\n",
"\n",
"