AC is when the electrons flow in two directions, from the positive to the negative terminal and from the negative to the positive terminal, 'alternating' between the two directions. A lot of people think of electron flow as electrons moving along a wire freely like cars go down a highway.
To check the status of protected mode, choose File > Properties > Advanced > Protected Mode. Protected mode is enabled by default. To specify the settings, do the following: Choose Edit > Preferences. In the Categories list on the left, select Security (Enhanced). In the Sandbox Protections section, select or deselect Enable Protected Mode At Startup. Enable Create Protected Mode Log File to record events. The changes take effect the next time you start the application.
EXAMPLE: Internet Explorer Protected Mode in Internet Explorer 8. NOTE: Only in Internet Explorer 8 you will see what security zone you are in at the bottom right in the status bar in, and whether protected mode is turned on or off for that security zone. This is not displayed in IE9, IE10, and IE11.