Question

1. Explain with the help of a diagram how the intensity and direction of the
magnetic field of a bar magnet can be determined.
2. Why is a magnetic needle used in a compass?
3. Give detailed information about how the merchants of olden times used a magnet while travelling.

Answer 1

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$\bold{\underline{\star\; \color{pink}{{Your \; Required \; Answers \; are \; as \; follows:}}}}$

1. Explain with the help of a diagram how the intensity and direction of the  magnetic field of a bar magnet can be determined.

$:\implies$ ❖ The intensity of magnetic field is indicated by the magnetic lines of  force in that particular area.

❖ Intensity of magnetic field in a particular area can be understood by  the number of field lines passing perpendicular through that unit  area.

❖ The intensity of magnetic field is more where the lines of force are  more concentrated.

❖ The direction of magnetic field is determined by the directions of  magnetic lines of force.

❖ The magnetic lines of force always start from the north pole and end  on the south pole.

❖ In the similar manner, the direction of magnetic field is form north  pole to south pole.

2. Why is a magnetic needle used in a compass?

$:\implies$ ❖ The magnetic needle used in a compass freely rotates and always  settles in the north-south direction as it is a property of a magnet

❖ Thus, a magnetic needle can be used to ascertain the direction.  Hence, magnetic needle is used in a compass.

3. Give detailed information about how the merchants of olden times used a magnet while travelling.

$:\implies$ ❖ The merchants of olden times used to carry compass for ascertaining  Directions while travelling.

❖ In a compass, a magnetic needle is fitted. This magnetic needle  supported on a sharp point can freely rotate in horizontal plane

❖ If a traveller goes anywhere while travelling, due to the property  of a magnet, magnetic needle always get settled in the north-south  direction.

❖ Once, the north direction is known, other directions can be easily  known.

❖ At the oceans where only water is seen everywhere or at the desert  areas where only sand is seen everywhere, it becomes difficult to  know the direction at night.

❖ At that time, the compass used to be helpful for merchants to know  the directions.

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