A correctly adjusted single phase 240 V induction watt-hour meter has a meter constant of 600. revolutions per kWh. Determine the speed of the disc, for a current of 10 A flow for 1 minute at a power factor of 0.8 lagging. If the lag adjustment is altered so that the phase angle between voltage coil flux and the applied voltage is 86°. Calculate the error introduced at 0.5 of lagging.