Many mail order catalogs sell lamp dimmer disks. These disks, which you insert in the sockets of incandescent lamps, promise to reduce your electrical bills while making the light bulbs last virtually forever. Unfortunately, these disks simply reduce the power delivered to the bulbs' filaments so that they operate below their rated temperature and waste energy producing infrared light. The dimmer disk actually contains a single diode that forms a series circuit with the light bulb. AC current from the power line must flow through the diode and then through the filament (or vice versa). Overall, this diode reduces the power delivered to the filament by about a factor of two because
A)	the diode only allows current to flow in one direction so that during one half of each cycle of the AC power line, no current flows through the light bulb.
B)	the diode divides the current in half and only allows one half of that current to flow through the filament.
C)	the diode behaves like a filament so that there are two filaments in a series, with each of them receiving half the power that a single filament would receive.
D)	the diode halves the voltage of the current passing through the light bulb so that the power it receives is also halved.
Answer:A
Many mail order catalogs sell lamp dimmer disks. These disks, which you insert in the sockets of incandescent lamps, promise to reduce your electrical bills while making the light bulbs last virtually forever. Unfortunately, these disks simply reduce the power delivered to the bulbs' filaments so that they operate below their rated temperature and waste energy producing infrared light. The dimmer disk actually contains a single diode that forms a series circuit with the light bulb. AC current from the power line must flow through the diode and then through the filament (or vice versa). Overall, this diode reduces the power delivered to the filament by about a factor of two because
A)	the diode only allows current to flow in one direction so that during one half of each cycle of the AC power line, no current flows through the light bulb. B)	the diode divides the current in half and only allows one half of that current to flow through the filament. C)	the diode behaves like a filament so that there are two filaments in a series, with each of them receiving half the power that a single filament would receive. D)	the diode halves the voltage of the current passing through the light bulb so that the power it receives is also halved.