15. henry; h
16 . the permeability of the core
The figure below shows a battery connected to a coil through a switch.
In the following figure, the coil is inserted into a second coil whose terminals are connected to a meter.
The coil connected to the current source (battery) is called the PRIMARY; the coil connected to the load
(meter) is called the SECONDARY.
When the switch is closed, the magnetic field building out from the primary will cut the windings of the
secondary, which induces an emf in the secondary. Note the meter direction.