Umthetho kaSnell ku-Refraction of Light
Ukwehlukaniswa kokukhanya kuyinto ebalulekile ekuqondeni ukuthi ukukhanya kuhlangana kanjani nemidiya ehlukahlukene. Omunye wemithetho eyisisekelo esetshenziswa ukuchaza ukwehlukaniswa kokukhanya uMthetho kaSnell. Lesi sihloko sizoxoxa ngoMthetho kaSnell ngokuningiliziwe, sihlanganisa isizinda sawo somlando, izimiso eziyisisekelo, amafomula ezibalo, ukusetshenziswa, kanye nezibonelo.
Isizinda Somlando
UMthetho kaSnell uqanjwe ngegama likaWillebrord uSnellius (1580–1626), isazi sezibalo nesazi sezinkanyezi saseDashi. Nakuba uSnellius athola lo mthetho ngo-1621, umqondo wokukhanya okukhanyayo ubulokhu waziwa kusukela ezikhathini zasendulo. Ososayensi abanjengoPtolemy no-Ibn Sahl babenze ucwaningo lwakuqala ngalesi simo, kodwa uMthetho kaSnell unikeza indlela enembile yezibalo.
USnellius wathola ukuthi lapho ukukhanya kudlula emngceleni phakathi kwemidiya emibili ehlukene, njengomoya namanzi, noma umoya nengilazi, imisebe yokukhanya iyagoba—into eyaziwa ngokuthi ukugqama. Lesi simo singachazwa ngumthetho oyisisekelo manje owaziwa ngokuthi uMthetho kaSnell.
Izimiso Eziyisisekelo Zomthetho KaSnell
Umthetho kaSnell uchaza ubudlelwano phakathi kwe-engeli yokwenzeka kanye ne-engeli yokukhanya okukhanyayo njengoba kudlula emngceleni ophakathi kwemidiya emibili enezinkomba zokukhanya ezihlukile. Isimiso esiyisisekelo salo mthetho singafingqwa kanje:
\[
n_1 \isono(\theta_1) = n_2 \isono(\theta_2)
\]
Di mana:
– \( n_1 \) yinkomba yokubuyisa yendlela yokuqala.
– \( \theta_1 \) yi-engeli ye-incidence, okungukuthi i-engeli ephakathi komsebe we-incidence kanye nomugqa ojwayelekile emngceleni we-medium.
– \( n_2 \) yinkomba yokubheka emuva yendlela yesibili.
– \( \theta_2 \) yi-engeli yokugqagqana, okuyi-engeli ephakathi komsebe ogqagqanisiwe nomugqa ojwayelekile emngceleni we-medium.
Inkomba Yokubukeza
Inkomba yokukhanya (\( n \)) ye-medium iyi-constant echaza ukuthi ukukhanya kuzogoba noma kuzokwenyuka kangakanani uma kungena kuleyo medium. Inkomba yokukhanya yakhiwe kanje:
\[
n = \frac{c}{v}
\]
Lapho \( c \) kuyijubane lokukhanya ku-vacuum kanye \( v \) kuyijubane lokukhanya ku-medium. Isibonelo, inkomba yokukhanya komoya cishe ingu-1,0, kuyilapho inkomba yokukhanya kwengilazi cishe ingu-1,5.
Incazelo Ebonakalayo Yokuhlukaniswa Kokukhanya
Ukukhanya okukhanyayo kungachazwa kusetshenziswa izimiso eziyisisekelo ze-optics. Uma ukukhanya kungena endaweni enenkomba ehlukile yokukhanya, amanye amandla okukhanya ayadluliselwa kanti amanye ayabonakaliswa. Ingxenye edluliselweyo idlula ekushintsheni kwesivinini, okubangela ushintsho endleleni eya kuyo. Yingakho ingilazi ingenza izinto ezingemuva kwayo zibonakale zigobile noma zisusiwe.
Ukuqhekeka kuphinde kuthintwe ubude bokukhanya. Lesi simo saziwa ngokuthi ukuhlakazeka, futhi singabonakala lapho ukukhanya okumhlophe kudlula ku-prism, kukhiqize ububanzi bemibala. Ukuhlakazeka kwenzeka ngoba ukukhanya okunama-wavelength ahlukene kuyaphambuka ngama-engeli ahlukene lapho kudlula endaweni ene-refractive index engalingani.
Izibonelo Zokusetshenziswa Komthetho KaSnell
1. I-Fiber Optics: Ukusetshenziswa okusebenzayo koMthetho ka-Snell kusebuchwephesheni be-fiber optic. I-Fiber optics yizintambo ezenziwe ngengilazi noma ipulasitiki encane ezisebenzisa izimiso zokukhanya kanye nokukhanya kwangaphakathi okuphelele ukudlulisa idatha. Ukukhanya okuthunyelwa nge-fiber optics kuhlala kuqondiswa futhi kuboniswe eceleni kwekhebula, okuvumela idatha ukuthi idluliselwe ngesivinini esikhulu nangamabanga amade.
2. Amalensi Nezibuko: Amalensi kuma-microscope, ama-telescope, amakhamera, kanye nezibuko zonke zakhiwe ngokusekelwe ku-Snell's Law. Ngokuhlanganisa amalensi enziwe ngezinto nezinto ezithile ezibonisa ukukhanya, singagxila ekukhanyeni ukuze sithuthukise umbono noma sikhulise izithombe zezinto ezikude noma ezincane kakhulu.
3. I-Prismatics kanye ne-Dispersion: Ama-Prism asetshenziswa kumathuluzi okukhanya ukuhlukanisa ukukhanya ngokusekelwe kubude bawo. Ukuhlakazeka, noma ukuhlukaniswa kokukhanya kube yimibala ehlukahlukene, kwenzeka ngenxa yokwehluka kwenkomba yokukhanya yama-wavelength ahlukene okukhanya. Umthetho kaSnell usiza ukuchaza ukuthi ukukhanya kugoba futhi kuhlukaniswe kanjani ku-prism.
4. I-Magic Head: Imiphumela ebonakalayo njenge-mirages nayo iyizibonelo zokukhanya okukhanyayo. Ngaphansi kwezimo ezithile, umehluko ekuxineni komoya (ngakho-ke inkomba yayo yokubuka) ingabangela ukukhanya ukugoba ngendlela eyenza izinto ezikude zibonakale zingaphezu komhlabathi noma amanzi.
Imibuzo Nezixazululo Eziyisampula
Ukuze siqonde kangcono ukusetshenziswa koMthetho kaSnell, ake sibheke isibonelo senkinga elula:
> Umbuzo: Umsebe wokukhanya uvela emoyeni ungene emanzini nge-engeli yokwenzeka kwe-\( 30^\circ \). Uma inkomba yokukhanya komoya ingu-1 (n_1) kanti inkomba yokukhanya kwamanzi ingu-1,33 (n_2), iyini i-engeli yokukhanya emanzini (θ_2)?
Isixazululo:
Ukusebenzisa ifomula kaSnell's Law:
\[
n_1 \isono(\theta_1) = n_2 \isono(\theta_2)
\]
Ngokufaka esikhundleni \( n_1 = 1 \), \( \theta_1 = 30^\circ \), kanye \( n_2 = 1,33 \):
\[
1 \isono(30^\circ) = 1,33 \isono(\theta_2)
\]
Kusukela \( \sin(30^\circ) = 0.5 \):
\[
0.5 = 1.33 \isono(\theta_2)
\]
\[
\sin(\theta_2) = \frac{0.5}{1.33} \cishe kube ngu-0.375
\]
Uma sithatha i-arc sine engu-0.375, sithola:
\[
\theta_2 \cishe \sin^{-1}(0.375) \cishe 22^\circ
\]
Ngakho-ke, i-engeli yokuphambuka cishe ingama-22^\circ \).
Isiphetho
UMthetho kaSnell uyisimiso esiyisisekelo ku-optics esichaza ukujikijelwa kokukhanya njengoba kudlula emngceleni phakathi kwemidiya emibili enezinkomba ezahlukene zokujikijelwa. Ukuqonda lo mthetho kusenza sikwazi ukuklama amadivayisi ahlukahlukene okujikijelwa awusizo kakhulu empilweni yansuku zonke, kusukela ezibukweni zamehlo kuya ezinhlelweni zokuxhumana ze-fiber-optic. Le ngxoxo iphinde ibonise ukuthi uMthetho kaSnell udlala indima ebalulekile kanjani ezimweni zemvelo zokujikijelwa esizibona nsuku zonke.
