If a voter is unable by reason of physical disability or inability to read the English or Spanish language to mark his ballot or to mark same in an informed manner he may, if he declares to the judge of the election, under oath, that he is so disabled or unable to read, and the judge of the election is satisfied, from the contents of the voter's registration card or other convincing proof, as to the truth of such declaration, have the assistance of a person of his own selection to mark his ballot or to read the ballot for him. Such person so selected shall be sworn, may accompany the voter into the voting booth, and shall either mark the ballot as directed by the voter in the case of physical disability or read the ballot to the voter in the case of inability of the voter to read, and shall thereafter give no information regarding the same. Such person so selected may assist only one voter in any primary or general election.