question: What is a watt balance ?
answer: an instrument for comparing two powers , one of which is measured in SI watts and the other of which is measured in conventional electrical units
turker_answer: A watt balance is an instrument for comparing two powers , one of which is measured in SI watts and the other of which is measured in conventional electrical units .
rule-based: A watt balance is an instrument for comparing two powers , one of which is measured in SI watts and the other of which is measured in conventional electrical units .