retrolefty:
Henry_Best:
Riccarr:
Also, I do believe a DC current flowing in either direction will magnetize the solenoid.The current direction determines which direction the solenoid pulls/pushes.
Are you sure? A DC relay pulls in no matter the polarity of the applied DC voltage. [/quote]
A relay pulls in to complete a magnetic 'circuit'. The top of the relay coil is one pole (depending on the direction of the current flow) and the bottom is the other pole. The iron frame of the relay connects the bottom pole to the armature, which is attracted to the top of the relay (opposite pole). So, as you say, a relay pulls in whichever direction the current is flowing.
A solenoid doesn't (usually) have that magnetic circuit, just a coil and a movable core.
A solenoid if using a non-magnetized armature should pull in also regardless of the applied polarity. AC solenoids would be very dramatic if applied polarity effected if polarity determined if it should pull or push on the armature. =(
Lefty
I see your point, so I'm not quite as sure now...