For the two port network shown in Fig. the admittance matrix is

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