If at the election two-thirds of the qualified electors who vote assent to the issuance of the bonds, the city or city and county may, by ordinance, or in such manner as other municipal legislative acts are enacted by it, provide for the issuance of, and cause to be issued, its bonds to the amount specified and voted for.
The bonds shall mature and become due and payable at a time not exceeding 20 years, and shall bear interest at a rate not exceeding 8 percent a year, payable annually. Before or at the time of the issuance of the bonds, provision shall be made for the collection of an annual tax sufficient to pay the interest as it falls due, and to constitute a sinking fund to pay the principal at maturity.