I-Physics Eyisisekelo Yokukhanya
Ukukhanya kungenye yezinto zemvelo ezihlobene kakhulu nokuphila komuntu. Sidinga ukuthi sikubone, sikusebenzisele ubuchwepheshe (kusukela kumakhamera kuya kuma-fiber optics), futhi sikufunde ukuze siqonde isakhiwo esiyisisekelo sendawo yonke. Ku-physics, ukukhanya kubhekwa njengohlobo lwamandla olungasakazeka, lusebenzisane nezinto, futhi lubonise izakhiwo ngezinye izikhathi ezibonakala zifana namagagasi futhi ngezinye izikhathi zifana nezinhlayiya. Lesi sihloko sihlanganisa kafushane kodwa ngokuningiliziwe i-physics eyisisekelo yokukhanya: incazelo yaso, izakhiwo zamagagasi, izakhiwo zezinhlayiya, ukusebenzisana nezinto, kanye nezinye izinhlelo zokusebenza.
1. Kuyini Ukukhanya?
Ngokomzimba, ukukhanya kuyigagasi likagesi elingasakazeka ngaphandle kwe-medium. Lokhu kusho ukuthi akudingi umoya noma enye "into ephakathi" ukuze kuhambe. Yingakho ukukhanya kwelanga kungafinyelela eMhlabeni ngesikhala esiseduze nesikhala.
Ukukhanya okungabonakala ngeso lomuntu kubizwa ngokuthi ukukhanya okubonakalayo, ngamaza obubanzi asukela cishe ku-400 nm (violet) kuya ku-700 nm (red). Ngaphandle kwalelo banga, kunezinye izinhlayiya ze-electromagnetic ezifana ne-infrared, i-ultraviolet, ama-microwave, umsakazo, kanye nama-X-ray. Konke lokhu empeleni "kuyizihlobo" zokukhanya, kuhluka kuphela ngobude bamaza namandla.
2. Ukukhanya njengegagasi le-Electromagnetic
Ku-theory ye-electromagnetic (eyakhiwe ezibalweni zikaMaxwell), ukukhanya kuqukethe amasimu kagesi namagnetic ajikelezayo aqonde komunye nomunye futhi aqonde ngqo endaweni yokusabalala. Lolu hlobo lwamagagasi lunikeza ukukhanya izici eziningana ezibalulekile:
a. Ubude begagasi kanye nemvamisa
– Ubude be-wave (λ) yibanga eliphakathi kwama-wave crests amabili alandelanayo.
– Imvamisa (f) inani lokudlidliza ngomzuzwana.
– Zombili zihlobene nesivinini sokukhanya (c) ngokusebenzisa i-equation:
c = λ f
Ku-vacuum, ijubane lokukhanya licishe libe ngu-3 × 10⁸ m/s. Leli nani libhekwa njengenye yezinto eziyisisekelo zemvelo. Kodwa-ke, lapho ukukhanya kungena endaweni efana namanzi noma ingilazi, ijubane lakho liyehla.
b. Amandla kanye nobudlelwano bawo nemvamisa
Nakuba sikhuluma ngobude besikhathi kanye nemvamisa kumongo wamagagasi, amandla okukhanya ahlobene kakhulu nemvamisa. Uma imvamisa iphakeme (uma ubude besikhathi bufushane), amandla aba maningi.
3. Ukukhanya njengezinhlayiya: Ama-photon
Ekuqaleni kwekhulu lama-20, izivivinyo eziningana zabonisa ukuthi incazelo yamaza kuphela ayanele. Lokhu kwaholela emcabangweni wokuthi ukukhanya kungabhekwa njengamaphakethe amandla ahlukene abizwa ngokuthi ama-photon. Amandla e-photon anikezwa yi:
E = hf
lapho u-h eyisiguquguquki sikaPlanck.
Lo mbono ubalulekile ekuchazeni izenzakalo ezifana nomphumela we-photoelectric, lapho ukukhanya okushaya khona indawo yensimbi kubangela ukuthi ama-electron akhishwe. Ngokuthakazelisayo, ama-electron akhishwa kuphela uma imvamisa yokukhanya iphakeme ngokwanele, noma ngabe amandla aphansi. Lokhu kusikisela ukuthi amandla okukhanya afika "ngamaconsi" (ama-photon), kunokuba kube umfudlana oqhubekayo njengoba kucatshangwa kumodeli wamagagasi akudala.
Ekuphetheni, ukukhanya kunobubili be-wave-particle: ngaphansi kwezimo ezithile kusebenza njengegagasi, futhi ngaphansi kwezinye izimo kusebenza njenge-particle.
4. Ukusebenzisana Kokukhanya Nezinto Ezibalulekile
Uma ukukhanya kuhlangana nento, kunezinto eziningana ezingenzeka: kungabonakaliswa, kuguqulwe, kufakwe, noma kudluliselwe. Lokhu kuziphatha kuncike ezicini zezinto kanye nobude bokukhanya.
a. Ukuzindla
Ukukhanya kwenzeka lapho ukukhanya kugxuma kusuka endaweni ethile, njengesibuko. Umthetho wokukhanya uthi:
– I-engela yokwenzeka = i-engela yokuzindla
– Umsebe wesigameko, umugqa ojwayelekile, kanye nomsebe obonisiwe kusendizeni efanayo.
Ukuzindla kungaba:
– Okuvamile (okukhethekile): ubuso obubushelelezi njengesibuko, buveza isithombe esicacile.
– Ukusabalala: izindawo ezimahhadlahhadla njengephepha, zibonakala ngezindlela ezahlukene ukuze kungabikho mthunzi obukhali owakhekayo.
b. Ukwehlukaniswa
Ukufiphaza ukukhanya ukushintsha indlela yokukhanya njengoba kudlula ezindaweni ezimbili ezahlukene, isibonelo kusuka emoyeni kuya emanzini. Lokhu kwenzeka ngoba ijubane lokukhanya liyashintsha ezindaweni ezahlukene. Inkomba yokufiphaza (n) ichazwa kanje:
n=c/v
lapho u-v kuyijubane lokukhanya endaweni ephakathi.
Ukuphinda kuhlanzwe kuchaza izenzakalo zansuku zonke: utshani bubonakala bugobile uma bubekwa engilazini yamanzi, noma phansi kwechibi kubonakala kungajulile kunalokho okuyikho ngempela.
c. Ukuhlakazeka
Ukuhlakazeka kuwukuhlukaniswa kokukhanya kube yimibala ehlukene ngenxa yokwehluka kokugqama kwamaza ahlukene. Ama-prism abelokhu ehlukanisa ukukhanya okumhlophe kube yimibala ehlukahlukene kusukela ekuhlolweni kukaNewton. Ama-rainbow nawo angumphumela wokuhlakazeka nokugqama kokukhanya kwelanga ngamaconsi amanzi emkhathini.
d. Ukumuncwa Nokukhishwa Kwezinto Ezingcolile
Izinto zingamunca amandla okukhanya athile; la mandla avame ukuguqulwa abe ukushisa. Ngokuphambene nalokho, izinto zingakhipha nokukhanya (okukhipha ukukhanya), njengezibani ze-incandescent noma izinkanyezi. Esikalini se-athomu, ukukhishwa kwenzeka lapho ama-electron ehamba esuka ezingeni lamandla aphezulu aye ezingeni eliphansi futhi ekhulula ama-photon.
5. Ukuhlukaniswa Okukhanyayo
I-Polarization iyisici esibonisa indlela yokudlidliza kwensimu kagesi kugagasi lokukhanya. Ukukhanya kwemvelo (isibonelo, okuvela eLangeni) kuvame ukungapholi, okusho ukuthi indlela yayo yokudlidliza ayihlelekile. Kodwa-ke, ukukhanya kungapholishwa ngesihlungi se-polarizing noma ngokukhanya nge-engeli ethile.
I-Polarization inezinhlelo eziningi zokusebenza: Izibuko ze-Polaroid zinciphisa ukukhanya, izikrini ze-LCD zisebenzisa isimiso se-polarization, kanti ku-physics yanamuhla i-polarization isiza ekuhlaziyweni kwezinto ezibonakalayo kanye nesayensi yezinkanyezi.
6. Ukuphambuka Nokuphazamiseka: Ubufakazi Bemvelo Yamagagasi
Izenzakalo ezimbili ezibalulekile ezibonisa uhlangothi lwamagagasi okukhanya yilezi:
– Ukuphazamiseka: ukuqina noma ubuthakathaka bokukhanya lapho amagagasi amabili ehlangana. Isibonelo, iphethini yokukhanya-ubumnyama ekuhlolweni kukaYoung kokuqhekeka okuphindwe kabili.
– Ukuphambuka: ukugoba kokukhanya njengoba kudlula embobeni encane noma onqenqemeni lwento. Lokhu kuchaza ukuthi kungani izithunzi zingenazo njalo izinhlangothi ezibukhali ngokuphelele.
Ukuhlolwa kwe-double-slit kudume ngokubonisa iphethini yokuphazamiseka enamandla. Ngisho noma ama-photon edutshulwa eyodwa ngesikhathi, iphethini yokuphazamiseka iyaqhubeka ngemva kokuba ama-photon amaningi eqongelelekile. Lokhu kubonisa isici esiyingqayizivele se-quantum: ukukhanya akunakuchazwa kuphela njenge-particle yakudala noma igagasi lakudala.
7. Ukusetshenziswa Komqondo Wokukhanya Kubuchwepheshe
Ukuqonda ukukhanya kwazala ubuchwepheshe obuningi besimanje, isibonelo:
– Amalensi kanye nezibuko: izibuko, ama-microscope, ama-telescope.
– I-Laser: isetshenziswa emisebenzini yezokwelapha, ekusikeni kwezimboni, kuma-barcode scanner, ezokuxhumana, kanye nocwaningo.
– I-fiber ye-optical: ithumela idatha ye-inthanethi isebenzisa ukukhanya okunokulahlekelwa okuncane ngokukhanya kwangaphakathi okuphelele.
– Amakhamera nezinzwa: I-CCD/CMOS iguqula ama-photon abe amasignali kagesi, isebenzisa imiphumela ye-quantum.
Ubuchwepheshe busebenza ngoba siyaqonda ukuthi ukukhanya kuhamba kanjani, kusebenzelana kanjani nezinto, futhi kuthwala amandla.
Isiphetho
Ukukhanya kuyinto ecebile futhi eyisisekelo ku-physics: kuyigagasi likagesi elihamba ngokushesha elakhiwe ama-photon, i-quanta yamandla. Sisebenzisa imiqondo yobude be-wavelength, imvamisa, i-refractive index, ukuzindla, ukugqama, ukuphazamiseka, ukuphambuka, kanye nokuhlukaniswa, singachaza izenzakalo eziningi zemvelo futhi siklame ubuchwepheshe obubalulekile. Ukuqonda i-physics eyisisekelo yokukhanya kusho ukuqonda olunye "lwezilimi" eziyisisekelo zendawo yonke—ukuxhumanisa isikali se-athomu, impilo yansuku zonke, kanye nendawo yonke.
Uma uthanda, ngingangeza imifanekiso yemiqondo (isb. imidwebo yokushintshashintsha, i-electromagnetic spectrum, noma ukuhlolwa kwe-double-slit) noma ngenze inguqulo ethandwa kakhulu yalesi sihloko yabafundi besikole samabanga aphakathi/aphezulu.
