# Electric Fields – (Part 2 of 2)

Part 1 of Electric Fields is here: Electric Fields (Part 1 of 2)

- F
_{e}= K | q_{1}q_{2}| / r^{2}

- The further away, the weaker the electric fields force becomes.
- Eventually, the force won’t be attracted enough, and it won’t reach the opposite charge:

## Electrical Potential Energy

Remember that `P`

_{e} = m . g . h

P

_{e}= Gravitational potential energym is the mass, g is gravity, and h is the height

- Work = Force of Gravity (F
_{g}) × Height (h) - W = F
_{g}× h

Electrical potential energy is very similar to gravitational potential energy.

For example:

**Moving A to position B**- Electric field strength: E = 5 N/c
- Field force = F
_{f}= 5 N/c × 2 c = 10 N - Distance between A, and B is 3 meters

↑ **.** A (+2 c) ↑ ↑ ↑ ↑ ↑

↑ **.** B (+ 2c) ↑ ↑ ↑ ↑ ↑

_____________________________

< ++++++++++++++++++++++++++ > (this is an infinite plate)

#### Q. How much work does it take to move a +2 c charge, down 3 meters?

The plate is positively charge – as is the ‘floating’ charge, so these forces will repel each other.

- Total upward force:
- F
_{f}= 5 N/~~c~~× 2~~c~~= 10 N - Work = 10 N × 3 m
- Work = 30 N/m = 30 J of energy

The electrical potential energy: P_{e} _{(Pa relative to Pb)} = 30 J

This is NOT electric potential – this is

electrical potential energy

*Electric potential = work / charge = 30 J / 2 c = 6 J/c = 6 V (Volts, Voltage)*

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