# Electric Fields

From: Optimusprime113 & physick.wikispaces.com

## What is a Electric Field?

• It is the field that a charged object gives off that attracts opposite charges and repels similiar charges. Like gravity.
• This repulsion between similiar charges causes a zero electric field between the two objects
• All electrically charged objects create electric fields.
• The E-Field of an object is represented by field lines and the more field lines the greater the E-Field is.
• The E-field is the direction a positive charged object would move when placed in the field.
 Top Left: just single charged particals Top Right: a positive and negative charge interacting with each other Bottom: different variations of charges interacting with each other.

• E-Fields are vectors, they have magnitude & direction
• the formulas used to find E-Field strength & magnitude are:
E= strength/magnitude of electric field (N/C)
Fe= Force of electric field (N)
q= charge on object (C)
k= Coulomb's Constant (8.99x10^9N*m^2/C^2)
Q= Charge on object (C)

## Uniform Electric Fields

### Pointed objects or sharp edged:

- The electric charge collects on the point or the edge of the object producing a stronger electric field then flat surfaces. It is not a uniform electric field but it can lead to a discharge into the air causing it to ionize and create plasma.
- If you look closely at the picture of the ship the blue lights coming the masts are called St. Elmo's fire which is actually plasma being created by the metal points discharging energy into the air.

### Solid Sphere's:

- When charged the charge spreads uniformly across the smooth surface.
- The field lines act are perpendicular to the surface of the sphere

### Hollow Sphere's:

- It is similiar to a solid sphere by how the charge spreads out uniformly
- But because of the idea that opposite charges cancel each other out, the centre of the sphere becomes an area that has a zero electric field.
- This amazing discovery led to the ideas of the Faraday cage which is a metalic container created by Michael Faraday and a cable called Coaxial Cable which has a copper mesh around the wire both of these are made to prevent interfrence with electric and magnetic fields near by.
- The picture here shows a man using a Faraday style suit to prevent the Tesla Coil's from shocking him

### Parallel Plates:

- If two conducting plates are charged a uniform field is produced between them
- The field produced would also only exist between the plates and a little out of them.
- The formula used to find the electric field that is produced between the plates is:

E= Electric Field (N/C)
V: Potential Difference or Voltage (J/m or V)
d: Distance (m)

##### References

1. Unknown, (June 3, 2012), http://www.kentshillphysics.net/EM3.htm
2. Mr. Langdale , (June 5, 2012), http://ldindustries.ca/LDIndustries/P30/LangdalePhysics30.html