Permittivity

polarizability khoom txheej yog yus muaj los ntawm ib tug tshwj xeeb muaj nqis, uas yog hu ua dielectric permittivity. Xav txog dab tsi zoo ntawm tus nqi.

Xav hais tias hais tias ib tug uniform teb siv nruab nrab ntawm ob daim hlau them nyob rau hauv lub tshuab nqus tsev sib npaug zos rau E₀. Tam sim no sau tej kis ntawm tus dielectric. Electric nqi, uas yuav tshwm sim nyob rau ciam ntawm lub dielectric thiab tus neeg xyuas pib vim hais tias ntawm nws cov polarization nyhuv cov neutralized cov nqi rau cov phiaj. Cov kev siv ntawm lub E teb siv yuav tsawg E₀.

Kev qhia tau hais tias thaum sau cov kis ntawm cov successive daim hlau sib npaug zos dielectrics, lub teb siv yuav sib txawv. Yog li ntawd, paub qhov sib raug zoo ntawm cov kev siv ntawm hluav taws xob field of cov phiaj nyob rau hauv lub qhaj ntawv ntawm dielectric E₀ thiab E nyob rau hauv lub xub ntiag ntawm lub dielectric, nws yog ua tau los mus txiav txim lub polarizability, i.e. nws dielectric qhov. Qhov no kom muaj nuj nqis feem ntau yog denoted los ntawm cov Greek tsab ntawv ԑ (epsilon). Thiaj li, peb yuav sau:

ԑ = E₀ / E.

Permittivity qhia tau hais tias yuav ua li cas muaj ntau zaus lub teb lub dag lub zog ntawm tus nqi ntaub ntawv nyob rau hauv lub insulator (homogeneous) yuav tsum tau tsawg tshaj li nyob rau hauv vacuo.

Txo tus quab yuam kev sis raug zoo ntawm cov nqi los ntawm cov txheej txheem ntawm polarization ntawm qhov nruab nrab. Nyob rau hauv ib qho hluav taws xob field, electrons nyob rau hauv lub atoms thiab molecules yog txo nrog hwm rau ions, thiab muaj yog ib tug dipole lub sij hawm ntawd. Xws li cov molecules uas muaj ib tug dipole lub sij hawm ntawd (tshwj xeeb yog dej lwg me me), yog taw qhia kom paub nyob rau hauv ib tug hluav taws xob field. Cov sij hawm tsim lawv tus kheej fais teb uas yog counteracts lub teb uas tshwm sim los ntawm lawv cov tsos. Raws li ib tug tshwm sim, tag nrho cov hluav taws xob field yog txo. Nyob rau hauv me me teb no tshwm sim yog piav los ntawm lub tswvyim ntawm tus dielectric qhov.

Hauv qab no yog cov permittivity nyob rau hauv lub tshuab nqus tsev tshuaj:

Cua ................................. 1,0006 ....

Paraffin .............................. .... 2

Plexiglas (Plexiglas) ...... 3-4

Ebonite ................................. .. ... 4

Iav ................................. .... 7

Khob .............................. .. ...... .4-7

Mica ................................. .. ... .4-5

Txhob lo lo ntxhuav yog ib yam ............ 4-5

Slate .............................. 6-7

Amber .............................. ... ...... 12,8

Dej .................................... ... ... .81

Cov tshuaj permittivity qhov tseem ceeb xa mus rau qhov kub thiab txias tsis pub dhau 18-20 ° C. Yog li, lub dielectric qhov ntawm cov khib nyiab mas nws txawv me ntsis nrog rau kub, tsuas tshwj cov ferroelectrics.

On qhov tsis tooj, nws decreases roj vim ua kub thiab ua vim qhov zuj zus siab. Nyob rau hauv kev xyaum, cov dielectric qhov ntawm huab cua yog muab raws li ib tug.

Lub impurities nyob rau hauv me me muaj me ntsis ntxim rau cov theem ntawm dielectric qhov kua.

Yog hais tias ob tug arbitrary point nqi tso rau hauv lub insulator, lub teb siv generated los ntawm txhua tus ntawm cov nqi ntawm tus taw tes qhov twg lwm them nyiaj tsawg ԑ lub sij hawm. Los ntawm no nws raws li nram no uas tus quab yuam uas cov nqi nrog txhua lwm yam, raws li nyob rau hauv ԑ lub sij hawm tsawg. Yog li ntawd, Coulomb txoj cai rau nqi tso rau hauv lub dielectric yog muab los ntawm:

F = (q₁q₂) / (ԑₐr²).

nyob rau hauv SI units :

F = (q₁q₂) / (4πԑₐr²)

qhov twg F - yog tus quab yuam kev sis raug zoo, q₁ thiab q₂, - kom muaj nuj nqis ntawm cov nqi ԑ - nws yog lub meej permittivity ntawm qhov nruab nrab, d - qhov kev ncua deb ntawm taw tes nqi.

Ԑ txog zauv tus nqi yuav muab tso tawm kom nyob rau hauv arbitrary units (tus txheeb ze rau tus tsis muaj nuj nqis ntawm cov tshuab nqus tsev permittivity ԑ₀). Tus nqi ԑ = ԑₐ / ԑ₀ hu ua tus kwv tij permittivity. Nws qhia ntau npaum li cas lub sij hawm sis rau cov nqi nyob rau hauv ib tug infinite homogeneous nruab nrab yog weaker tshaj nyob rau hauv ib lub tshuab nqus; ԑ = ԑₐ / ԑ₀ feem ntau hu ua lub complex dielectric qhov. Ԑ₀ txog zauv tus nqi, thiab nws dimension yog nyob rau qhov zoo ntawm cov chav nyob yog xaiv; thiab tus nqi ԑ - ywj siab. Yog li, nyob rau hauv lub system ԑ₀ esu = 1 (qhov no plaub lub ntsiab chav tsev); Lub SI lub tshuab nqus tsev permittivity yog qhia los ntawm:

ԑ₀ = 1 / (4π˖9˖10⁹) farad / meter = 8,85˖10⁻¹² f / m (nyob rau hauv no system yog ԑ₀ derivative tus nqi).