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# System prepended metadata

title: Physics II - B2 - Electric Field

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# Physics II - B2 - Electric Field

## Introduction
* The ***electric force*** is a ***field force.*** 
* Field forces can ***act through space.***
* The effect is produced even ***with no physical contact*** between objects.

## Definition
* An <span style="color: red">electric field</span> is said to **exist** in the region of space **around a charged object.** (source charge)
* The **electric field** is defined as the **electric force** on the test charge **per unit charge.**

![Electric Field](https://i.imgur.com/Kma9qpD.png)

## Electric Field Lines (Đường sức từ)
* go out from the positive, go into the negative.
* cannot split, merge, cross each other.
* Number of field lines attached a charge ~ the amount of charge.
<img src = "https://i.imgur.com/uKM500M.png" width = 700 height = 450>

## Motion of Charged Particles
![image alt](https://i.imgur.com/NOPsFLv.png)

## Uniform Electric Field (Điện trường đều)
* Eletron's motion is parabolic while between the plates.

<img src = "https://i.imgur.com/S4opAsb.png" width = 600 height = 300>


## Continuos Charge Distribution
<img src = "https://i.imgur.com/FCMTJFv.png" width="570" height="400">

## Assignment
<img src = "https://i.imgur.com/9W3InKB.png" width="590" height="290">

$$
dE = \frac{k.dq}{x^2 + r^2}
$$

$$
\frac{dE_x}{dE} = \frac{x}{(x^2 + r^2)^\frac{1}{2}}
$$

$$
dE_x = \frac{x}{(x^2 + r^2)^\frac{1}{2}}.\frac{k.dq}{x^2 + r^2}
$$

We have $dE_y = 0$. So:

$$
E = E_x = \int dE_x
= \int \frac{kx.dq}{(x^2 + r^2)^\frac{3}{2}} = \frac{kx}{(x^2 + r^2)^\frac{3}{2}}.Q
$$

## New Words
* **radial altitude:** Máy đo độ cao vô tuyến
* **vanish:** biến mất

## Other references
* [MIT Physics 2](https://www.youtube.com/playlist?list=PLyQSN7X0ro2314mKyUiOILaOC2hk6Pc3j)
* [Michel van Biezen](https://www.youtube.com/playlist?list=PLX2gX-ftPVXX7BZOcM1Y2gb8IQrTBrmUB)
