Ka'idar Bohr, wanda kuma aka sani da samfurin Bohr ko samfurin Rutherford-Bohr, ka'idar kimiyya ce da masanin kimiyyar Danish Niels Bohr ya gabatar a shekara ta 1913. Ya bayyana tsarin atom da yadda electrons ke motsawa a kusa da tsakiya. p> Bisa ga ka'idar Bohr, ana shirya electrons a cikin zarra a matakan makamashi, ko harsashi, a kusa da tsakiya. Kowane harsashi yana da kafaffen matakin makamashi kuma yana iya ɗaukar takamaiman adadin electrons. Electrons na iya motsawa daga wannan matakin makamashi zuwa wani ta hanyar sha ko fitar da makamashi a cikin nau'i na photons.Ka'idar Bohr kuma ta yi bayanin layukan da aka gani a cikin nau'in atomic spectra. Lokacin da na'urar lantarki ta motsa daga mafi girman matakin makamashi zuwa matakin ƙananan makamashi, yana fitar da makamashi a cikin nau'i na photon tare da takamaiman tsayin raƙuman ruwa. Tsawon tsayin photon ya yi daidai da bambancin makamashi tsakanin matakan makamashi guda biyu.Ka'idar Bohr ta kasance muhimmiyar gudummawa ga haɓaka injiniyoyin ƙididdiga, kuma ya taimaka wajen bayyana abubuwa da yawa na atom da halayensu. Duk da haka, tun daga lokacin an maye gurbinsa da ƙarin nagartattun ƙirar ƙirar ƙira.