Understanding Electric Field Lines: An Introduction to E Bar and Tangent Vectors

[Andy_Taiwanese]

Hi, I'm reading the textbook and there is my image.
http://imgur.com/a/9BqHm

It says "The field vector E bar is tangent to the electric field line at each point".
I might want to ask what "tangent" means in this sentence? Sorry to ask that stupid question.

 

[cnh1995]

I might want to ask what "tangent" means in this sentence?

Do you know what a tangent is in geometry?
This wiki article will help.
https://en.m.wikipedia.org/wiki/Tangent

https://en.m.wikipedia.org/wiki/File:Graph_of_sliding_derivative_line.gif
You can visualize how the E-field will be on curved field lines.

 

[olgerm]

It means any electricfield-line is parallel with electricfield vector $\vec E$ at any point.

 

[Andy_Taiwanese]

Do you know what a tangent is in geometry?
This wiki article will help.
https://en.m.wikipedia.org/wiki/Tangent

https://en.m.wikipedia.org/wiki/File:Graph_of_sliding_derivative_line.gif
You can visualize how the E-field will be on curved field lines.

Thank you!