An energy meter revolves 10 revolutions of disc for unit of energy. Find the number of revolutions made by it during an hour when connected across whe

Energy consumed in one hour = VI cos φ / 1000
= 210 x 20 x 0.8 / 1000
= 3.360 kwh.

The number of revolution the meter should make it is correct
= 3.360 x registration const in revolution per kwh
= 3.360 x 100
= 336Number of revolution actually made
= 350
% error = (350-336) x 100 / 350
% error = 0.1466 %