3. The coil of a moving iron instrument has a resistance of 500 ? and an inductance of 1 H. It reads 250 V when a 250 V dc is applied. If series resistance is 2000 ?, its reading when fed by 250 V, 50 Hz ac will be
All wattmeters measure average power over a cycle.
7. A meter with a resistance of 100 ? and a full scale deflection of current of 1 mA is to be converted into voltmeter of 0 - 5 V range. The multiplier resistance should be