Ma'anar ƙamus na "ɗakin ƙarfin filin" (FSU) shine naúrar ma'auni da ake amfani da ita a cikin electromagnetism don bayyana ƙarfin filin lantarki ko maganadisu. Naúrar ƙarfin filin shine adadin vector, kuma ana bayyana girmansa cikin ma'aunin volts a kowace mita (V/m) don filayen lantarki da amperes a kowace mita (A/m) don filayen maganadisu. FSU ana yawan amfani da ita wajen auna siginar watsa shirye-shiryen rediyo da talabijin, da kuma a binciken kimiyya da injiniyanci da suka shafi filayen lantarki.