SiHuan's Wiki求带电体周围某处的场强
带电量为$+q_1$的点电荷.
场强大小:
$$E=\frac{q}{4 \pi \varepsilon_{0} r^{2}}$$
方向:由点电荷向外为正方向.
半径为$R$,带电量为$q$的均匀带电球壳
场强大小:
$$\mathrm{E}=\left\{\begin{array}{l}{0, \quad \mathrm{球内}} \\ {\frac{\mathrm{q}}{4 \pi \varepsilon_{0} \mathrm{r}^{2}}, \quad \mathrm{球外}}\end{array}\right.$$
方向:由球心向外为正方向.
半径为$R$,带电量为$q$的均匀带电球体
场强大小:
$$E=\left\{\begin{array}{l}{\frac{q}{4 \pi \varepsilon_{0} R^{3}} r}, \quad \mathrm{球内}\\ {\frac{q}{4 \pi \varepsilon_{0} r^{2}},\quad \mathrm{球外}}\end{array}\right.$$
方向:由球心向外为正方向.
线电荷密度为$\lambda$的无限长均匀带电直线
场强大小:
$$
\mathrm{E}=\frac{\lambda}{2 \pi \varepsilon_{0} \mathrm{r}}
$$
方向:
Sunita 19:38
Hello. How may I help you?
Si Huan 19:39
hi
I got smoe errors when I use wolfram mathematica download manager to download Mathematica 12.
like this
Sunita 19:39
Do you have your Activation Key? I can check the status.
Si Huan 19:40
yes i have a try key
my english is poor
Sunita 19:40
Can you provide me with the Mathematica Activation Key?
Si Huan 19:40
Your trial activation key is 4409-0795-PG3K8L.
Sunita 19:41
One moment, pelase.
*Please
Si Huan 19:42
ok ok
Sunita 19:42
What is your operating system?
Si Huan 19:42
mac os version:10.15.2
Sunita 19:44
Have you tried using a different browser? Like Firefox.
It may be caused by a firewall on your side.
Yes
Si Huan 19:44
You mean use a different to download the Download Manager?
You mean use a different browser to download the Download Manager?
Sunita 19:45
Can you try using Firefox browser?
Sunita 19:51
Ok, I am checking if they are any other options.
Si Huan 19:51
Actually there is no firefox browser on my computer. I downloaded (Download Manager for Wolfram Mathematica 12) using chrome. And it didn't work.
I think it has nothing to do with what browser I use
Can I get an offline installation package.Just like “Mathematica_12_Chinese_Mac.dmg”
My English is not good. If my tone is weird or impolite, please forgive me
Sunita 19:55
I will need to refer you to the our U.S support team. to provide you with an alternative link
It is ok, I understand you completely.
https://wolfr.am/Jqi4KVAB try the following link, please.
Si Huan 19:56
Thank you!
Sunita 19:57
Let me know if this works for you.
Si Huan 19:58
I can open the link. And is it the Chinese version?
Sunita 19:58
Yes, it is.
Si Huan 19:59
Thank you. It works. I am downloading it
Sunita 19:59
Good News! Thanks.
It was nice talking to you. Have a great day, goodbye!
Si Huan 20:00
Good bye. Have a great day.
Read
Sunita 20:00
Bye.
Sunita has closed the chat.