Electric fields, (refereed to as e-fields,) provide a structure in space to apply a force to any body with a net charge. Electric fields can be controlled with multiple charges. Batteries are great sources of free charges. The typical setup for studying electric fields is shown below.
![e-field setup](pics/e_field_plates_n_batteries.png)
The plate connected to the positive side of the bateries get a positive charge. The plate connected to the negative side of the batteries becomes negatively charged. The e-field is defined as the path a positive particle would travel. In this diagram above a positive particle would travel to the plate connected to the negative side of the battery.
The electric field is between the two plates is defined by
![](pics/VEd_Equation.gif)
E:
d:
ΔV: |
electric field [N/C] or [v/m]
distance betweenthe plates [m]
Potential difference acros the two surfaces [v] |
As a particle travels from one plate the other the amount of work done is equal to qV.
![Work equals qV](pics/W_equals_qv.gif)
q:
V: |
the particle's net charge, [C]: Coulombs
is the potential difference of the power source, [v]: volts |
This means that the energy lost or gained as a charged particle crosses the plates is equal to qV. Because the amounts of energy are so small they are measured in electronVolts, eV's.
![eV to Joule conversion Equation](pics/eV_Conversion.gif)
If a particle with a charge equal to a single elementaty charge, such as an electron or proton, travels across an electric field made by a battery, then the energy lost of gained equals the (# of elementary charges)x(the battery voltage) = eV's. Energy is lost of the opposite plate is the same sign as the particle and t is gained if the opposite plate is the opposite sign of the particle.
![](pics/2plates.png)
For example: If the plates above are connected to a 12 volt battery, then an electron would gain 12 eV's of energy. A proton would lose 12 eV's of energy.
Example 2: If a particle with a charge equal to 3 elctrons travels between the plates while they are conencted to a 5
volt battery then the particle would gain (3)(5) = 15 eV's of energy.
Another important characteristic of an e-field is the fact that it can also guide charge particles. If we could create the e-field below, charges would travel around the corner.
![](pics/e_field_corner.png)
As it turns out, this is easily done with a conducting wire.
![](pics/E_field_corner_wire.png)
This is because the electric field travels along the outside of the wire to move the charges in a current.
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