A sinusoidal source of voltage $$V$$ and frequency $$f$$ is connected to a series circuit of variables resistance, $$R$$ and a fixed reactance, $$X.$$ The locus of the tip of the current phasor, $$I$$, as $$R$$ is varied from $$0$$ to $$\infty $$ is

The effective inductance of the circuit across the terminals $$A,B$$ in the Figure shown below is

A moving coil galvanometer is made into a d.c. ammeter by connecting

A d.c. voltmeter has a sensitivity of $$1000$$$$\Omega /volt.$$ When it measures half full scale in $$100$$ $$V$$ range, the current through the voltmeter is