Question

The directive property of magnet is used in
A. Construction of compass
B. Construction of transformer
C. Construction of generator
D. All of these

Answer 1

Hint: The directive property of a magnet is the tendency of the magnet to align freely on the horizontal plane itself as per earth’s magnetic field. Let us take an example, when a magnet is suspended freely in air with help of a thread it aligns itself in geographical north-south direction. This is the directive property of magnet.

Complete step by step answer:
Compass is an instrument which shows direction relative to geographical cardinal points. It is used for navigation and orientation purposes of ships and many other cases. The directive property of compass is used in compasses where a small magnet is present where the needle is pointed towards the north. Noting the crown mark on the compass navigators determine the magnetic north and to determine geographical north at a place angle of declination should be collected from the magnetic maps.
Transformers work on the principle of mutual induction between a pair of coils. Transformer is used to increase or decrease alternating voltage by using step-up and step-down transformers respectively.
Electric generator converts mechanical energy into electric energy with the help of the principle of electromagnetic induction.
So, the correct answer is (a) construction of compass.

Note:Variation of elements of earth’s magnetism is different at different positions on earth. But the value of the elements at different places on earth’s surface may be the same. The places on earth’s surface possessing the same value of a particular element are joined by a line. The geographical lines containing such lines are called magnetic maps. From magnetic maps of different components the declination angle of a particular place is determined which is used to determine the direction by using compass.