2014 dxdy logo

Научный форум dxdy

Математика, Физика, Computer Science, Machine Learning, LaTeX, Механика и Техника, Химия,
Биология и Медицина, Экономика и Финансовая Математика, Гуманитарные науки




 
 Задача по теме "Электростатика"
Сообщение25.11.2011, 17:41 
Помогите разобраться с задачей..

На расстоянии $ % MathType!MTEF!2!1!+-
% feaagCart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn
% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr
% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9
% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x
% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamyyaiabg2
% da9iaaigdacaaIWaaaaa!3955!
\[a = 10\]$ см от бесконечной, равномерно заряженной плоскости находится центр равномерно заряженного кольца радиуса $% MathType!MTEF!2!1!+-
% feaagCart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn
% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr
% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9
% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x
% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamOuaiabg2
% da9iaaiwdaaaa!3890!
\[R = 5\]$. Ось кольца параллельна плоскости. Определить напряженность результирующего поля в точке, находящейся на оси кольца на расстоянии в=R от центра кольца. Поверхностная плотность заряда на плоскости $% MathType!MTEF!2!1!+-
% feaagCart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn
% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr
% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9
% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x
% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaeq4Wdmhaaa!37B7!
\[\sigma \]=2 мкКл/м^2$, линейная плотность заряда на кольце $% MathType!MTEF!2!1!+-
% feaagCart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn
% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr
% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9
% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x
% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaeqiXdqhaaa!37B9!
\[\tau \]=1 мкКл/м


$

Дано

$ % MathType!MTEF!2!1!+-
% feaagCart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn
% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr
% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9
% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x
% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamyyaiabg2
% da9iaaigdacaaIWaaaaa!3955!
\[a = 10\]$ см = 2R

$% MathType!MTEF!2!1!+-
% feaagCart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn
% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr
% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9
% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x
% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamOuaiabg2
% da9iaaiwdaaaa!3890!
\[R = 5\]$ см

$% MathType!MTEF!2!1!+-
% feaagCart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn
% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr
% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9
% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x
% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamOmeiabg2
% da9iaadkfacqGH9aqpcaaI1aaaaa!3A51!
\[ b= R = 5\]$ см

$% MathType!MTEF!2!1!+-
% feaagCart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn
% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr
% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9
% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x
% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaeq4Wdmhaaa!37B7!
\[\sigma \]=2 мкКл/м^2$

$% MathType!MTEF!2!1!+-
% feaagCart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn
% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr
% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9
% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x
% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaeqiXdqhaaa!37B9!
\[\tau \]=1 мкКл/м

$% MathType!MTEF!2!1!+-
% feaagCart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn
% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr
% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9
% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x
% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaeqyTduMaey
% ypa0JaaGymaaaa!395C!
\[\varepsilon  = 1\]$ - Диэлектрическая проницаемость

$% MathType!MTEF!2!1!+-
% feaagCart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn
% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr
% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9
% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x
% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaWaaubeaeqale
% aacaaIWaaabeqdbaGaeqyTdugaaOGaeyypa0JaaGioaiaac6cacaaI
% 4aGaaGynaiaacQcacaaIXaGaaGimamaaCaaaleqabaGaeyOeI0IaaG
% ymaiaaikdaaaaaaa!4154!
\[\mathop \varepsilon \nolimits_0  = 8.85*{10^{ - 12}}\]$ ф/м - Электрическая проницаемость.



Найти

$% MathType!MTEF!2!1!+-
% feaagCart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn
% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr
% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9
% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x
% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamyraaaa!36BE!
\[E\]$ - ?



Решение


Посчитав, у меня получилось напряженность поля на оси кольца

$% MathType!MTEF!2!1!+-
% feaagCart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn
% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr
% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9
% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x
% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaWaaubeaeqale
% aacaaIXaaabeqdbaGaamyraaaakiabg2da9maavababeWcbaGaaGym
% aaqab0qaaiaadweaaaGccqGH9aqpdaWdbaqaaiaadsgacaWGfbGaai
% OkaiGacogacaGGVbGaai4Caiabeg7aHjabg2da9maapeaabaGaamiz
% aiaadweadaWcaaqaaiaadggaaeaadaGcaaqaaiaadggadaahaaWcbe
% qaaiaaikdaaaGccqGHRaWkcaWGsbWaaWbaaSqabeaacaaIYaaaaaqa
% baaaaaqabeqaniabgUIiYdaaleqabeqdcqGHRiI8aOGaeyypa0Zaa8
% qaaeaadaWcaaqaaiaadggacaWGXbaabaGaaGinaiabec8aWjabew7a
% LnaavababeWcbaGaaGimaaqab0qaaiabew7aLbaakiaacIcadaGcaa
% qaaiaadggadaahaaWcbeqaaiaaikdaaaGccqGHRaWkcaWGsbWaaWba
% aSqabeaacaaIYaaaaOGaaiykamaaCaaaleqabaGaaGOmaaaaaeqaaa
% aaaeqabeqdcqGHRiI8aOGaeyypa0ZaaSaaaeaacaWGHbaabaGaaGin
% aiabec8aWjabew7aLnaavababeWcbaGaaGimaaqab0qaaiabew7aLb
% aakiaacIcadaGcaaqaaiaadggadaahaaWcbeqaaiaaikdaaaGccqGH
% RaWkcaWGsbWaaWbaaSqabeaacaaIYaaaaOGaaiykamaaCaaaleqaba
% GaaG4maaaaaeqaaaaakmaapeaabaGaamizaiaadghaaSqabeqaniab
% gUIiYdaaaa!74CD!
\[\mathop E\nolimits_1  = \mathop E\nolimits_1  = \int {dE*\cos \alpha  = \int {dE\frac{a}{{\sqrt {{a^2} + {R^2}} }}} }  = \int {\frac{{aq}}{{4\pi \varepsilon \mathop \varepsilon \nolimits_0 (\sqrt {{a^2} + {R^2}{)^2}} }}}  = \frac{a}{{4\pi \varepsilon \mathop \varepsilon \nolimits_0 (\sqrt {{a^2} + {R^2}{)^3}} }}\int {dq} \]$

Продолжение

$% MathType!MTEF!2!1!+-
% feaagCart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn
% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr
% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9
% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x
% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaWaaubeaeqale
% aacaaIXaaabeqdbaGaamyraaaakiabg2da9maalaaabaGaamyyaiaa
% dghaaeaacaaI0aGaeqiWdaNaeqyTdu2aaubeaeqaleaacaaIWaaabe
% qdbaGaeqyTdugaaOGaaiikamaakaaabaGaamyyamaaCaaaleqabaGa
% aGOmaaaakiabgUcaRiaadkfadaahaaWcbeqaaiaaikdaaaGccaGGPa
% WaaWbaaSqabeaacaaIZaaaaaqabaaaaOGaeyypa0ZaaSaaaeaacaaI
% YaGaamOuaiaadghaaeaacaaI0aGaeqiWdaNaeqyTduMaaiikamaaka
% aabaGaaGinaiaadkfadaahaaWcbeqaaiaaikdaaaGccqGHRaWkcaWG
% sbWaaWbaaSqabeaacaaIYaaaaOGaaiykamaaCaaaleqabaGaaG4maa
% aaaeqaaaaakiabg2da9maalaaabaGaaGOmaiaadkfacqaHepaDcaaI
% YaGaeqiWdaNaamOuaaqaaiaaisdacqaHapaCdaqfqaqabSqaaiaaic
% daaeqaneaacqaH1oqzaaGccaWGsbWaaWbaaSqabeaacaaIZaaaaOGa
% aiOkaiaaicdacaGGUaGaaGimaiaaiwdacaGGQaGaaGimaiaac6caca
% aI1aaaaiabg2da9maalaaabaGaeqiXdqhabaWaaubeaeqaleaacaaI
% WaaabeqdbaGaeqyTdugaaOGaamOuaiaacQcacaaIWaGaaiOlaiaaic
% dacaaI1aGaaiOkaiaaicdacaGGUaGaaGynaaaacqGH9aqpdaWcaaqa
% aiaaigdacaaIWaWaaWbaaSqabeaacqGHsislcaaI2aaaaaGcbaGaaG
% ioaiaac6cacaaI4aGaaGynaiaacQcacaaIXaGaaGimamaaCaaaleqa
% baGaeyOeI0IaaGymaiaaikdaaaGccaGGQaGaaGimaiaac6cacaaIWa
% GaaGynaiaacQcacaaIWaGaaiOlaiaaiwdaaaGaeyypa0JaaGinaiaa
% c6cacaaI1aGaaGOmaaaa!9031!
\[\mathop E\nolimits_1  = \frac{{aq}}{{4\pi \varepsilon \mathop \varepsilon \nolimits_0 (\sqrt {{a^2} + {R^2}{)^3}} }} = \frac{{2Rq}}{{4\pi \varepsilon (\sqrt {4{R^2} + {R^2}{)^3}} }} = \frac{{2R\tau 2\pi R}}{{4\pi \mathop \varepsilon \nolimits_0 {R^3}*0.05*0.5}} = \frac{\tau }{{\mathop \varepsilon \nolimits_0 R*0.05*0.5}} = \frac{{{{10}^{ - 6}}}}{{8.85*{{10}^{ - 12}}*0.05*0.5}} = 4.52\] МВ$


Напряженность поля на бесконечной плоскости

$% MathType!MTEF!2!1!+-
% feaagCart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn
% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr
% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9
% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x
% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaWaaubeaeqale
% aacaaIYaaabeqdbaGaamyraaaakiabg2da9maalaaabaGaeq4Wdmha
% baGaaGOmamaavababeWcbaGaaGimaaqab0qaaiabew7aLbaaaaGccq
% GH9aqpdaWcaaqaaiaaikdacaGGQaGaaGymaiaaicdadaahaaWcbeqa
% aiabgkHiTiaaiAdaaaaakeaacaaIYaWaaubeaeqaleaacaaIWaaabe
% qdbaGaeqyTdugaaaaakiabg2da9iaaicdacaGGUaGaaGymaiaaigda
% caaIYaaaaa!4BFA!
\[\mathop E\nolimits_2  = \frac{\sigma }{{2\mathop \varepsilon \nolimits_0 }} = \frac{{2*{{10}^{ - 6}}}}{{2\mathop \varepsilon \nolimits_0 }} = 0.112\]$ МВ



....

Подскажите, может ли так много получаться?



И еще, как применить принцип суперпозиции в данной задаче...

 
 
 
 Re: Задача по теме "Электростатика"
Сообщение25.11.2011, 18:04 
Аватара пользователя
 !  Оформляйте читабельно. Переехали.

 
 
 [ Сообщений: 2 ] 


Powered by phpBB © 2000, 2002, 2005, 2007 phpBB Group