(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.
As long as there is movement in the PIR field of view the lighting will stay ON. Any movement of a heat source could cause the sensor to switch the lighting on. (including hot air movement) i.e. draughts from an open window or door, air vents. close by, cars in the street or movement in the neighbours property. This depends. on the angle of the sensor head and the distance from the sensor.