Electric Field
Discussion
Introduction
Some text and some diagrams. The electric field as a vector field.
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and so on… |
And more diagrams. The electric field as field lines.
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and so on… |
And maybe some mathematics. In classical field theory, the strength of the field at a point is the normalized value of the field. In other words…
| field = | force |
| quantity |
For electricity, this becomes…
| E = | FE |
| q |
There is no special name for its unit, nor does it reduce to anything simpler.
| ⎡ ⎢ ⎣ |
N | = | kg m/s2 | = | kg m | ⎤ ⎥ ⎦ |
| C | A s | A s3 |
We will see later that this is equivalent to…
| ⎡ ⎢ ⎣ |
N | = | V | ⎤ ⎥ ⎦ |
| C | m |
For point charges…
| E = | 1 | q | r̂ | or | E = k | q | r̂ | |
| 4πε0 | r2 | r2 |
For multiple point charges…
| E = | 1 | ∑ | dq | r̂ | or | E = k ∑ | dq | r̂ |
| 4πε0 | r2 | r2 |
For continuous charge distributions…
| E = | 1 | ⌠ ⌡ |
dq | r̂ | or | E = k | ⌠ ⌡ |
dq | r̂ |
| 4πε0 | r2 | r2 |
| E (V/m) | device, event, phenomenon, process |
|---|---|
| 5.0 × 10−7 | shark, threshold of sensitivity |
| 120 | Earth's surface (sea level) |
| 3 × 106 | dielectric breakdown of air |