<prompt> Typically rapid palatal expansion is done with a jack screw that is activated at the rate of:1.0 to 2.0 mmweek1.0 to 2.0 mmday0.5 to 1.0 mmweek0.5 to 1.0 mmday  <response>: Every turn of the screw opens the appliance by 0.25 mm. Each turn involves 90 activation. With rapid maxillary expansion at a rate of 0.51 mmday, a 10 mm expansion is achieved in 23 weeks.Textbook of ORTHODONTICS Sridhar Premkumar 