Answer / poorna

control the speed of the fan by controlling voltage across
armature,(by varing the resistance the drop across the
resistance is changed and hence the voltage available
across armature is varied,). since torque is proportional
to square of voltage for induction motor, developed torque
and speed (as for fan load T prop to square of speed)speed
is changed

Answer / dev

in fan, inuction motor is used to drive the fan load.
the regulator of fan consists no. of resistance
contact...it changes the the resistance of ciruit.
in starting resistance is kept high for high starting
torque, at that time speed will be low..after this instant
resistances are slowly cut out...and speed will rise..

Answer / mahi&junu

switching the supply with the required resistance

Answer / mayur

the current is changed by the resistence so fan speed changed

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