Why are magnets with concave shaped poles used in DC motor?What happens if magnets with flat poles are used in it?

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Solution

dear student
A galvanometer needs to have a constant magnetic field through the magnetic circuit, so as to have a linear scale. The deflection of the armature, through which the current flows,needs to be proportional to the size of the current. This can only be easily done by using a cylindrical electromagnetic.A permanent magnet is designed to create the maximum magnetic fields between its poles. A concave shape produces the least possible air gap between the poles, making a strong magnetic circuit.
also if we use magnet which have flat poles then , since we require large amount of flux to pass through the core and magnetic flux depends on magnetic field lines so in flat poles magnetic filed lines will be less as compared to poles with concave poles. hence concave poles are preffered.
regards

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