Tātai Papa Hiko
He ariā taketake te papa hiko i roto i te ahupūngao e whakaahua ana i te pānga o te kaha hiko e pāngia ana e te utu hiko ki tētahi atu utu. I whakaurua tuatahitia tēnei ariā e Michael Faraday i te rautau 19, ā, kua waiho hei tūāpapa mō ngā hangarau hou maha, tae atu ki te hiko me te hikohiko. Ka matapakihia e tēnei tuhinga te whakamāramatanga o te papa hiko, te tauira taketake mō te papa hiko, me pēhea te tatau, me ōna whakamahinga i roto i te oranga o ia rā.
Te Mārama ki ngā Mara Hiko
Ko te papa hiko he whakaaturanga o te kaha e pāngia ana e te utu hiko nā te noho mai o ētahi atu utu i tōna taha. Mā te pāngarau, ko te papa hiko te kaha mō ia utu ka pā ki tētahi utu whakamātautau iti kua whakanohoia ki tētahi pūwāhi kua hoatu. Mēnā ka whakanohoia he utu pai ki roto i tētahi papa hiko, ka pāngia e te kaha i te ahunga kotahi me te papa, ko te utu kino ia ka pāngia e te kaha i te ahunga kē.
Te Tātai Taketake o te Papa Hiko
Ka taea te tatau i te papa hiko (\( \mathbf{E} \)) i tētahi pūwāhi i te wāhi i puta mai i tētahi utu pūwāhi \( Q \) mā te whakamahi i te tātai:
\[ \mathbf{E} = \frac{1}{4\pi \epsilon_0} \frac{Q}{r^2} \hat{r} \]
Kei hea:
– Ko te mara hiko (Newton ia Coulomb, N/C) te \( \mathbf{E}
– Ko te rahi o te utu (Coulomb, C) te \( Q \),
– Ko te \( r \) te tawhiti mai i te utunga ki te pūwāhi e tatauhia ai te āpure (mita, m),
– Ko \( \hat{r} \) he waeine whārite e tohu ana i te ahunga mai i te utunga ki te pūwāhi e tatauhia ai te āpure,
– Ko te \( \epsilon_0 \) te āheinga korehau (\( 8.854 \times 10^{-12} \, \text{C}^2/\text{Nm}^2 \)).
Te Taupatupatu o ngā Mara Hiko
I ngā wā maha, ko te papa hiko i tētahi pūwāhi he hua o ngā takoha mai i ētahi utu. E kī ana te mātāpono o te taupatupatu ko te papa hiko katoa i tētahi pūwāhi ko te tapeke o ngā papa hiko i puta mai i ia utu takitahi. Mā te pāngarau:
\[ \mathbf{E}_{\text{total}} = \mathbf{E}_1 + \mathbf{E}_2 + \mathbf{E}_3 + \ldots \]
Ko \( \mathbf{E}_i \) te mara hiko i puta mai i te utu \( Q_i \).
Papa Hiko mai i te Tohatoha Utu
Ehara i te mea ko ngā utu pūwāhi anake ka puta mai ngā mara hiko, engari ko ngā tohatoha utu tonu anō hoki. E rua ngā momo tohatoha utu e kitea whānuitia ana: ko ngā tohatoha utu rārangi me ngā tohatoha utu mata.
1. Tohatoha Utaina Raina
Mō te tohatoha utu rārangi, ka taea te tatau i te mara hiko i tētahi pūwāhi mā te whakauru i te takoha mara mai i ngā huānga utu iti i te taha o tētahi rārangi. Mena ka tohatohahia te utu i runga i te rārangi me te kiato utu rārangi \( \lambda \) (Coulombs ia mita), ko te mara hiko i tētahi pūwāhi \( P \) ko:
\[ \mathbf{E} = \frac{1}{4\pi \epsilon_0} \int \frac{\lambda \, dl}{r^2} \hat{r} \]
Ko \( dl \) te roa o te tohatoha utu, ā, ko \( r \) te tawhiti mai i te huānga \( dl \) ki te pūwāhi \( P \).
2. Te Tohatoha Utu Mata
Mō te tohatoha utu mata, ka taea te tatau i te mara hiko i tētahi pūwāhi mā te whakauru i ngā takoha mara mai i ngā huānga utu iti i runga i te mata. Mena ka tohatohahia te utu kia ōrite me te kiato utu mata \( \sigma \) (Coulombs ia mita tapawha), ko te mara hiko i tētahi pūwāhi \( P \) ko:
\[ \mathbf{E} = \frac{1}{4\pi \epsilon_0} \int \frac{\sigma \, dA}{r^2} \hat{r} \]
Ko \( dA \) te huānga horahanga o te tohatoha utu, ā, ko \( r \) te tawhiti mai i te huānga \( dA \) ki te pūwāhi \( P \).
Pūmanawa Hiko
Ko te pūmanawa hiko (\(V\)) he ariā e pā tata ana ki te mara hiko. Ko te pūmanawa hiko i tētahi pūwāhi ko te pūngao pūmanawa hiko mō ia wae utu e pāngia ana e te utu whakamātautau kua whakanohoia ki taua pūwāhi. Ko te whanaungatanga i waenga i te mara hiko me te pūmanawa hiko ka whakaaturia penei:
\[ \mathbf{E} = -\nabla V \]
Ko \( \nabla V \) te pikinga o te pūmanawa hiko. I te taha kotahi, ka taea te tuhi penei:
\[ E = -\frac{dV}{dx} \]
Ngā Whakamahinga o ngā Mara Hiko
He maha ngā whakamahinga nui o ngā mara hiko i roto i te oranga o ia rā me ngā hangarau hou. Ko ētahi tauira ko:
1. Kapasitor
He wāhanga hiko te pūnga hiko e pupuri ana i te pūngao i roto i te āhua o tētahi papa hiko. E rua ngā pereti arataki hiko e wehea ana e tētahi rauemi ārai-hiko. Ina pāngia ngā pereti ki tētahi utu hiko, ka hangaia he papa hiko i waenganui i a rāua, e pupuri ana i te pūngao hiko.
2. Pūhiko Van de Graaff
He taputapu te pūkaha hiko Van de Graaff e whakamahia ana hei whakaputa i ngā mara hiko teitei. Mā te whakawhiti i tētahi utu hiko ki tētahi porowhita whakarewa nui, ka hangaia he mara hiko tino kaha huri noa i a ia. He maha ngā wā ka whakamahia ēnei pūkaha hiko i roto i ngā whakamātautau ahupūngao, me te whakaatu i ngā pānga o te hiko pateko.
3. Ngā mata tirotiro CRT me ngā pouaka whakaata
Ka whakamahia e ngā mata tirotiro me ngā pouaka whakaata he ngongo hihi katote (CRT) ngā mara hiko hei whakahaere i te ara o ngā irahiko e tukuna ana ki te mata. Ka whakamahia ngā mara hiko me ngā mara aukume hei huri i ngā ara o ngā irahiko, ka hanga he ahua ki runga i te mata whōkawa.
4. Whakaahua Hauora
Ka whakamahia hoki ngā mara hiko i roto i ngā hangarau whakaahua hauora pēnei i te Magnetic Resonance Imaging (MRI). Ahakoa he nui ake te whakawhirinaki o te MRI ki ngā mara aukume, he mahi anō tā ngā mara hiko ki te whakahaere i ngā tohu reo irirangi hei whakaputa whakaahua o roto o te tinana.
Whakamutunga
Ko te papa hiko he ariā taketake i roto i te ahupūngao e whakaahua ana i te kaha e pā ana ki tētahi utu hiko ki tētahi atu utu. Mā te whakamahi i te tātai papa hiko taketake, ka taea e tātou te tatau i te papa hiko i puta mai i tētahi utu pūwāhi me tētahi tohatoha utu tonu. Mā te kaupapa o te taupatupatu ka taea e tātou te tāpiri i ngā takoha mai i ngā pūtake papa hiko rerekē hei whiwhi i te papa katoa i tētahi pūwāhi. Ko te pūmanawa hiko, e pā tata ana ki te papa hiko, e whakarato ana i tētahi atu huarahi ki te mārama ki te pūngao pūmanawa i roto i tētahi pūnaha hiko. He maha ngā tono nui a ngā papa hiko i roto i te oranga o ia rā me te hangarau hou, mai i ngā wāhanga hiko pēnei i ngā pūnga ki ngā taputapu whakaahua hauora matatau. Ko te māramatanga hohonu ake ki ngā papa hiko kei te akiaki tonu i te auahatanga me te ahunga whakamua i roto i ngā momo mara pūtaiao me te hangarau.
