Technician A says that magnetic lines of force can be seen by placing iron filings on a piece of paper and then holding them over a magnet. Technician B says that the effects of magnetic lines of force can be seen using a compass. Which technician is correct?

Both A and B are correct

Explanation:

Magnetic line of force can be seen by placing iron fillings on a piece of paper and then hold a magnet over them, the iron fillings align themselves in the magnetic field of the magnetic along the line of forces thus showing the loops of the magnetic line of forces. Also, we know that unlike poles attract where as like poles repel each other. This fact can be proved when we hang a bar magnet it aligns itself in the North-South direction because of the the magnetic field due to the alignment of the geographical North-South poles and the poles of the bar magnet and the compass works the same way.

Thus both the technicians are correct.

Technician A is correct

Magnetic lines of force can be seen by placing iron filings on a piece of paper and then holding them over a magnet.

Explanation:

As we know that the magnetic field lines are always originated out from the North pole of magnet and then terminate at south pole of the magnet

Here we know that when magnetic material aligns itself in the direction of external magnetic field

So here when we put the iron filings on the cardboard and then place a magnet near it then all the iron filing will align itself in the direction of the magnetic field

Now if we place a compass near the magnet then it will aligns itself in the tangential direction of the magnetic field at the same position

So here we can say that Technician A is correct