Q4 of 7 Page 42

Give reasons.

A magnetic needle is used in a mariner's compass.

Magnetic needle is used in a mariner's compass as Sailors use marine compass to locate directions.


Whenever a magnet is kept in such a situation, that it is fee to move in any direction on the surface of earth, it aligns or orient itself such that north pole of magnet points towards North Pole of earth and south pole towards south pole of earth, Magnetic needle in marine compass rotates to come to rest at north- south direction


This helps sailors to point north direction, with the help of which all other direction can be determined by mariner, and mariner can travel.


More from this chapter

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2

Match the following.

 3

Fill in the blanks.

(a) There is magnetic …….………. between like poles.


(b) Stainless steel is a …….………. substance.


(c) There is mutual attraction between …….………. poles of magnets.


(d) There is maximum magnetic force near the …………… of a magnet.

 4

Give reasons.

If a bar magnet is suspended vertically it does not hang in the north-south direction.

 1

Take a paper clip. Tie a fine black thread to it. Tie a knot to the other end of the thread and stick it to a table top. Now, bring a bar magnet above the clip. The magnet will lift the clip. Keep raising the bar magnet gradually. The clip, too, will rise till the thread becomes straight. If the magnet were hidden what would you see ? A clip that hangs in mid-air !