magnetic coil...
-
answer is A..i tot it becomes slightly weaker since its not a magnet then the iron bar draws the magnetism away?? -
comeon...
-
This is a solenoid without the iron bar.
This solenoid has a soft iron core which is more permeable to the magentic field than air is and as a result, creates a much stronger magnetic field. As a result, it is a much stronger electromagnet.
The iron actually becomes a magnet while placed in the existing field, influcing the magnetic field by producing a more "focused" or stronger field with more lines passing through itself. -
Main reason is because the iron core helps to focus the magnetic field lines within the core of the solenoid. In addition, because iron is a magnetic material, it is made of "tiny magnets", which are in random directions initially (making it neutral). The solenoid's magnetic field also helps to turn all these "tiny magnets" to the same direction, leading to a stronger magnetic field.