Question

1)

a. Do you think the brass and glass of a compass case affect the action of the compass needle? Explain why.

b. What could you use as a shield to protect a watch from becoming magnetized? Explain using physical principles.

c. If you used a different pole of a magnet, i.e., South instead of North, would your experimental results be different when testing objects for magnetism? Explain your answer using physical principles.

Answer 1

a) No. The glass and brass are not magnetic substances and so they will not attract the magnetic needle in the compass. Hence they will not have any effect on the working of the compass needle.

b) Any magnetic material like Iron, Nickel, Cobalt etc. can be used to shield the watch from getting magnetized. These magnetic materials are highly permeable to magnetic fields and so all the field lines pass through these materials only. Hence no field passes through the watch if kept inside the box made of magnetic material. This is known as magnetic shielding.

c) No! If we want to test if the given substance is magnetic or not then we can use any pole - South or North. Either pole of the magnet will be able to attract the magnetic substance with equal strength.