In the circuit shown in fig. For measuring resistance $$'R'$$ if the ammeter indicates $$1$$ $$A$$ and the voltmeter indicate $$100V$$, then the value of $$R$$ is ___________ Ohms and the error in measurement using the ratio $$V/$$$${\rm I}$$ is ________%

A dynamometer type wattmeter responds to the

A potentiometer is basically

A transfer instrument employed in the standardization of a polar type $$a.c$$ potentiometer is ______