Hello,

What do you call to the switch of the electric fan which often numbered 1, 2, 3, 4. 1 is the slowest and 4 is the fastest. Okay, not to mention the number zero which means off.

So, what do you call to that switch? Also how this switch works? How this switch fast and slow the electric fan?

Okay, how can I figure out the internal resistance of a battery?

Please, I need your help.

Any help would be appreciated.

Thank you so much.

 

I think the motor speeds are selected by having a multi-winding motor, or by a TRIAC.

Some of the cheapest fans having just three settings: 0, 1, 2 have a diode for speed "1" which slows it down considerably, and wire mains live to "2".

To measure internal resistance of a battery, attach a load resistor to it and measure the voltage drop; the drop is proportional to current, and the current will give you the resistance. Remember V = IR.