一、简介
相距为l的一对等量异号点电荷+q和-q,并且它们到观察点P的距离rl。通常的媒质分子在外电场的作用下可以形成这种电偶极子。电偶极子的特征用电偶极矩(或电矩)p＝lq表示，l和p的方向规定由-q指向+q。电矩p 的国际制单位为C·m（库·米）。微观物理学中常用的单位为德拜(debye)；1德拜＝3.336×10C·m，它相当于典型分子内部核间距离的十分之一(约2×10m)同一个电子的电荷e=1.6×10C的乘积。
电偶极子产生的电场＋q和－q分别在观察点P®产生的电位的代数和即电偶极子产生的电位
式中墷只对P点的坐标变量运算。在P点的电场强度为 。
外电场中的电偶极子若电偶极子＋q和－q所在点的外电场的电位为V1和V2,则偶极子的位能W=qV1-qV2=q(l·墷)V＝p·墷 V＝-p·Eo,式中Eo为点偶极子所在的外电场强度。
偶极子在外电场中受到平移力 F＝-墷W＝墷(p·Eo)＝(p·墷)Eo。
如果外电场均匀，Eo为常量，则F＝0。 偶极子在外电场作用下受到的力矩 T＝-дW／дθ＝pEosinθ或T＝p×Eo，它使电矩p同外电场强度Eo的夹角减小。如果p 同Eo平行，则力矩T＝0。并可看到p的量值也就是电偶极子在单位外电场(Eo=1)下可能受到的最大力矩，故称电矩。
如果点偶极子 p1 处于另一偶极子 p2 产生的电场E2®中，则p1的位能即相互作用能为电偶极子电偶极子
。
电偶极子是电介质理论和原子物理学的重要模型，研究从稳恒到 X光频电磁场作用下电介质的色散和吸收，以及天线的辐射等现象,可以用振荡偶极子poe电偶极子电偶极子
来表示。
将偶极子概念加以推广，可有多极子，它是含有2个大小相等的点电荷，其中正负各半数，排列成有规律的点阵。在多极子系列中，n＝0时，就是点电荷；n＝1，就是电偶极子；n＝2，称为四极子；n≥2，统称为高阶多极子。
高阶多级子模型应用于核物理，其中最重要的是四极子。任意点电荷集合或任意分布电荷，如果能够用一个球面包围,则球外的电位V可用集中在球心的点多极子系列的合成电位表示，称为电场的多极子展开。
二、源代码
function varargout = dianoujizi(varargin)
% dianoujizi MATLAB code for dianoujizi.fig
% dianoujizi, by itself, creates a new dianoujizi or raises the existing
% singleton*.
%
% H = dianoujizi returns the handle to a new dianoujizi or the handle to
% the existing singleton*.
%
% dianoujizi('CALLBACK',hObject,eventData,handles,...) calls the local
% function named CALLBACK in dianoujizi.M with the given input arguments.
%
% dianoujizi('Property','Value',...) creates a new dianoujizi or raises the
% existing singleton*. Starting from the left, property value pairs are
% applied to the GUI before dianoujizi_OpeningFcn gets called. An
% unrecognized property name or invalid value makes property application
% stop. All inputs are passed to dianoujizi_OpeningFcn via varargin.
%
% *See GUI Options on GUIDE's Tools menu. Choose "GUI allows only one
% instance to run (singleton)".
%
% See also: GUIDE, GUIDATA, GUIHANDLES
% Edit the above text to modify the response to help dianoujizi
% Last Modified by GUIDE v2.5 03-May-2013 20:22:55
% Begin initialization code - DO NOT EDIT
gui_Singleton = 1;
gui_State = struct('gui_Name', mfilename, ... %GUI结构
'gui_Singleton', gui_Singleton, ...
'gui_OpeningFcn', @dianoujizi_OpeningFcn, ...
'gui_OutputFcn', @dianoujizi_OutputFcn, ...
'gui_LayoutFcn', [] , ...
'gui_Callback', []);
if nargin && ischar(varargin{
1})
gui_State.gui_Callback = str2func(varargin{
1});
end
if nargout
[varargout{
1:nargout}] = gui_mainfcn(gui_State, varargin{
:});
else
gui_mainfcn(gui_State, varargin{
:});
end
% End initialization code - DO NOT EDIT
% --- Executes just before dianoujizi is made visible.
function dianoujizi_OpeningFcn(hObject, eventdata, handles, varargin)
% This function has no output args, see OutputFcn.
% hObject handle to figure
% eventdata reserved - to be defined in a future version of MATLAB
% handles structure with handles and user data (see GUIDATA)
% varargin command line arguments to dianoujizi (see VARARGIN)
set(handles.a_edit,'String',2); %设置默认值为2
set(handles.b_edit,'String',2); %设置默认值为2
% Choose default command line output for dianoujizi
handles.output = hObject;
% Update handles structure
guidata(hObject, handles);
% UIWAIT makes dianoujizi wait for user response (see UIRESUME)
% uiwait(handles.figure1);
% --- Outputs from this function are returned to the command line.
function varargout = dianoujizi_OutputFcn(hObject, eventdata, handles)
% varargout cell array for returning output args (see VARARGOUT);
% hObject handle to figure
% eventdata reserved - to be defined in a future version of MATLAB
% handles structure with handles and user data (see GUIDATA)
% Get default command line output from handles structure
varargout{
1} = handles.output;
function a_edit_Callback(hObject, eventdata, handles)
% hObject handle to a_edit (see GCBO)
% eventdata reserved - to be defined in a future version of MATLAB
% handles structure with handles and user data (see GUIDATA)
% Hints: get(hObject,'String') returns contents of a_edit as text
% str2double(get(hObject,'String')) returns contents of a_edit as a double
% --- Executes during object creation, after setting all properties.
function a_edit_CreateFcn(hObject, eventdata, handles)
% hObject handle to a_edit (see GCBO)
% eventdata reserved - to be defined in a future version of MATLAB
% handles empty - handles not created until after all CreateFcns called
% Hint: edit controls usually have a white background on Windows.
% See ISPC and COMPUTER.
if ispc && isequal(get(hObject,'BackgroundColor'), get(0,'defaultUicontrolBackgroundColor'))
set(hObject,'BackgroundColor','white');
end
function b_edit_Callback(hObject, eventdata, handles)
% hObject handle to b_edit (see GCBO)
% eventdata reserved - to be defined in a future version of MATLAB
% handles structure with handles and user data (see GUIDATA)
% Hints: get(hObject,'String') returns contents of b_edit as text
% str2double(get(hObject,'String')) returns contents of b_edit as a double
% --- Executes during object creation, after setting all properties.
function b_edit_CreateFcn(hObject, eventdata, handles)
% hObject handle to b_edit (see GCBO)
% eventdata reserved - to be defined in a future version of MATLAB
% handles empty - handles not created until after all CreateFcns called
% Hint: edit controls usually have a white background on Windows.
% See ISPC and COMPUTER.
if ispc && isequal(get(hObject,'BackgroundColor'), get(0,'defaultUicontrolBackgroundColor'))
set(hObject,'BackgroundColor','white');
end
% --- Executes on button press in eped_pushbutton.
function eped_pushbutton_Callback(hObject, eventdata, handles)
% hObject handle to eped_pushbutton (see GCBO)
% eventdata reserved - to be defined in a future version of MATLAB
% handles structure with handles and user data (see GUIDATA)
a=str2num(get(handles.a_edit,'String')); %获得默认值
b=str2num(get(handles.b_edit,'String'));
x=-8:0.8:8;
y=x;
q=2e-6; %电荷
k=9e9; %常数
[X,Y]=meshgrid(x,y);
rp=sqrt((X-a).^2+(Y-b).^2); %设置变量求出r-
三、备注
完整代码或者代写添加QQ2449341593
往期回顾>>>>>>
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