A couple years ago I compared heating water in a Hot Pot vs a Microwave. Today I tried this experiment with a Silex type container on a single burner electric element.
I have calculated that theoretically about 1.095 wH are required to heat 1 quart of tap water 1 degree C in the range above freezing and below boiling. Someone check my figure. My reference was the 40th edition of the Handbook of Chemistry and Physics, p 2107.
Using a Rival 4071WN hot pot and 1 quart (32 ounces) of tap water I measured an efficiency of 1.095/1.153 = 95%.
Using a GE microwave with the water in a 1 quart Pyrex measuring bowl the efficiency was 1.095/2.6 = 42%.
Today's test, the equivalent of a glass pot on an ordinary electric range top, showed an efficiency of 1.095/2.12 = 52%.
What happens when the test is performed with a cast iron pot on an induction heating range? One problem here is the large metal mass in relationship to the water mass.