Ma'anar dokar Ohm
A kusan dukkan masu sarrafa ƙarfe, filin lantarki yana daidai da yawan wutar lantarki, inda rabon filin lantarki da yawan wutar lantarki yake daidai. An bayyana shi ta hanyar lissafi ta hanyar lissafi:
ρ = E / J
E = ba filin lantarki, ρ = tsayayya, J = halin yanzu yawa
Ana kiran ρ mai ɗorewa da juriya, wanda ƙimarsa take dawwama kuma ba ta dogara da filin lantarki da ke haifar da wutar lantarki ba.
Idan filin lantarki ya ƙaru, yawan wutar lantarki ma yana ƙaruwa, yayin da idan filin lantarki ya ragu, yawan wutar lantarki ma yana raguwa.
don haka rabon filin lantarki da yawan wutar lantarki ya kasance mai dorewa. Wannan shine bayanin shari'a na Ohm. Don haka, lissafin da ke sama yana bayyana dokar Ohm ne kawai lokacin da ρ yake dawwama kuma bai dogara da filin lantarki ba. Dokar Ohm ba ta aiki idan darajar ρ ta canza lokacin da filin lantarki ya canza.
Duk da haka, yana da sauƙi a auna ƙarfin lantarki (V) fiye da filin lantarki (E), don haka yana da sauƙin auna wutar lantarki (I) fiye da yawan wutar lantarki (J). Saboda haka, ban da an faɗi a cikin filin lantarki, yawan wutar lantarki da juriya (ρ), dokar Ohm kuma an bayyana ta a cikin ƙarfin lantarki, ƙarfin lantarki da juriyar lantarki (R).
Da farko a sake duba na'urar sarrafa waya wacce ke da tsayi (l), yanki mai giciye (A) kuma akwai bambancin ƙarfin lantarki (V) tsakanin ƙarshen waya biyu. Idan filin lantarki iri ɗaya ne, to dangantakar da ke tsakanin filin lantarki da bambancin ƙarfin lantarki za a bayyana ta a cikin lissafin V = E s (an tattauna wannan lissafin a cikin ƙarfin lantarki). Idan yawan kwararar wutar lantarki iri ɗaya ne,
sannan dangantakar da ke tsakanin wutar lantarki da yawan wutar lantarki za a bayyana ta a cikin lissafin I = JA (an tattauna wannan lissafin a cikin batun wutar lantarki).
Domin samun lissafi wanda ke nuna alaƙar da ke tsakanin ƙarfin lantarki (V), ƙarfin lantarki (I) da juriyar lantarki (R),
maye gurbin E da J a cikin lissafin juriya, da E a cikin lissafin ƙarfin lantarki da J a cikin lissafin wutar lantarki:
Wannan lissafi ne da ke bayyana alaƙar da ke tsakanin ƙarfin lantarki (V), ƙarfin lantarki (I) da juriyar lantarki (R) a cikin mai jagora. Dangane da wannan lissafi, za a iya cewa juriyar lantarki a cikin mai jagora kwatancen bambancin ƙarfin lantarki da ƙarfin lantarki a cikin mai jagora.
Dokar Ohm ta bayyana cewa rabon da ke tsakanin bambancin ƙarfin lantarki da wutar lantarki yana dawwama. A wata ma'anar, wannan lissafi yana bayyana dokar Ohm ne kawai lokacin da juriyar lantarki (R) take dawwama. Dokar Ohm ba ta aiki idan juriyar lantarki ba ta dawwama ba.
A cikin lissafin da ke sama, juriyar wutar lantarki (R) a cikin mai jagora yana da alaƙa da juriya (ρ), tsawon mai jagora (l) da yankin giciye (A) na mai jagora. An bayyana shi ta hanyar lissafi a cikin lissafin:
Daidaito na dokar Ohm
An bayyana dokar Ohm ta hanyar lissafi biyu, wato ρ = E/J da R = V/I. Ya kamata a tuna cewa waɗannan lissafi guda biyu lissafi ne na dokar Ohm kawai lokacin da ρ yake da daidaito kuma R yana da daidaito. Idan ρ da R na mai jagoranci suka canza, waɗannan lissafi guda biyu ba sa bayyana dokar Ohm, amma ρ = E/J yana bayyana juriyar wani nau'in mai gudanarwa kuma R = V/I yana bayyana juriyar wutar lantarki na mai gudanarwa.
Ana iya rubuta lissafin ρ = E/J kamar haka E = ρ J. Idan ρ ya kasance mai daidaito, E yana daidai da J, ma'ana idan E ya ƙaru to J yana ƙaruwa ko kuma idan E ya ragu to J yana raguwa.
Haka nan, ana iya rubuta lissafin R = V/I a matsayin V = I R. Idan R ya kasance mai daidaito to V yana daidai da I kai tsaye, ma'ana idan V ya ƙaru, to ni ma na ƙaru ko kuma idan V ya ragu, to ni ma na ragu.
Ana cewa kayan da ke bin dokar Ohm suna da ohmic, yayin da kayan da ba sa bin dokar Ohm ana cewa ba su da ohmic. Kusan dukkan masu sarrafa ƙarfe suna da ohmic, yayin da sauran abubuwa da yawa ba su da ohmic.
A kan abubuwa marasa ohmic, juriyar lantarki ba ta canzawa kuma ta dogara ne akan wutar lantarki da bambancin yuwuwar wutar lantarki. Wannan yana nufin cewa idan wutar lantarki ta canza to juriyar lantarki na kayan ma yana canzawa, haka kuma idan wutar lantarki ta canza to juriyar lantarki na kayan ma yana canzawa. Saboda canjin juriyar lantarki fiye da na abu mara ohmic, ƙarfin lantarki (V) ba ya daidaita kai tsaye da wutar lantarki (I).
Jadawali na V, I da R
A cikin matter ohmic, rabon V zuwa I yana dawwama, wanda layi madaidaiciya ke wakilta. Misalin kayan ohmic shine mai sarrafa ƙarfe. A halin yanzu a cikin matter nohmic, rabon V zuwa I ba maiwwama bane, wanda layi mai lanƙwasa ke wakilta. Misalan kayan nohmic sune diodes na semiconductor da transistors.
Dokar Ohm ta shafi kayan ohmic ne kawai kuma ba ta shafi dukkan abubuwa ba, don haka bai dace a faɗi dokoki kamar dokar Newton ko wasu dokokin zahiri ba. Dokar zahiri ta shafi dukkan abubuwa, ba wai kawai ga wasu abubuwa ba. Amma ambaton dokar Ohm ya zama al'ada, don haka har yanzu ana kiranta dokar Ohm, muddin ana tuna cewa dokar Ohm ta shafi abubuwa ohmic ne kawai.
