If the number of turns in armature is made twice current 3 times and B - 4 times and area of armature is made half then speed of the motor becomes

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Solution

torque = number of turns * current* area * magnetic field

torque = NIAB

now changing current area and field

new torque = 2N* 3I(A/2) 4B
new torque = 12*NIAB
speed of rotation is propartational to torque so speed became 12 times.

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If the number of turns in armature is made twice current 3 times and B - 4 times and area of armature is made half then speed of the motor becomes

torque = number of turns * current* area * magnetic field torque = NIAB now changing current area and field new torque = 2N* 3I*(A/2)* 4B new torque = 12*NIAB speed of rotation is propartational to torque so speed became 12 times.

torque = number of turns * current* area * magnetic field

torque = NIAB

now changing current area and field

new torque = 2N* 3I(A/2) 4B
new torque = 12*NIAB
speed of rotation is propartational to torque so speed became 12 times.