Conversion of Electrical Energy to Heat

[ALLIRIX]

I've done a school experiment converting electrical energy to heat. P=VI was used to find the electric power going through the Ohmic heating coil, and got an answer of 30 watts. It was used to heat 0.2kg of water and the equation Q/t = m×c×T/t was used to find the Heating Power which gave an answer of 20 watts. I was wondering if the lower answer is only due to inefficiencies of the experiment or that not 100% of the power is converted and some remains in the heating element as electrical energy.

 

[Rellek]

Could be inconsistencies, power given off in other forms of energy, heat transferred into the air, or heat transferred into the container holding the water.