(1 + c)/(r + e + c). The money multiplier (also called the credit multiplier or the deposit multiplier) is a measure of the extent to which the creation of money in the banking system causes the growth in the money supply to exceed growth in the monetary base.
A buzzing light switch could mean the fixture is wearing out, causing an arc of electricity behind the wall plate. If this is the case, the potential for an electrical fire may exist.
How it works: in a switch loop, the hot and neutral wires arrive at the light fixture before reaching the switch. If you simply connected the wires from the light to the switch, the light would always be on. That would not only drive your electric bills way up, but it would burn out bulbs way too quickly.