What is a Field? FAQs & Answers

[ThinkerofWhat]

Homework Statement

Could you confirm or refute these ideas?
1) All fields start from a point charge.
2) We tend to measure the sum of fields from groups of point charges.
3) The inverse square portion of the field strength of a point charge is based on the geometry of the surface area of a sphere.
4) Ignoring any interferences from the environment, the sum of the strength of a field at a distance of a point charge is equal to the strength of the point charge.


QUESTIONS:
a) Does a field strength at a distance from a point charge exist because of a force or effect that is *moving* through space from the point through a distance? If so, what is the speed of a field ?

or

b) Does a field strength at a distance from a point charge exist because of an interaction with a medium in it's direct vicinity which then interacts with a medium in it's vicinity and so on? If so, what would the medium of vacuum consist of? How is it recognized?

Homework Equations

All inverse square field equations.

 

[davo789]

The reduction in strength is just a result of the fact that you are spreading the field lines more thinly. If you put a dot on a piece of paper and draw lines 15cm long coming from the dot evenly in all directions, you will see that the lines diverge. All a 'field strength' is, is the density of these lines.

The same occurs for the brightness of the sun (or anything else). The brightness (/field strength) is not dependent on time, but reduces with distance.

 

[ThinkerofWhat]

It's OK, I found a reasonable answer on Wikipedia.

http://en.wikipedia.org/wiki/Intensity_(physics)

Thanks.