A dc A-h meter is rated for 15 A, 250V. The meter constant is 14.4 A-sec/rev. The meter constant at rated voltage may be expressed as

The circuit in fig is used to measure the power consumed by the load. The current coil and the voltage coil of the watt meter have $$0.02$$ $$\Omega $$ and $$1000$$ $$\Omega $$ resistance respectively. The measured power compared to the load power will be

A moving coil of a meter has $$100$$ turns, and a length and depth of $$10$$ $$mm$$ and $$20$$ $$mm$$ respectively. It is positioned in a uniform radial flux density of $$200$$ $$mT.$$ The coil carries a current of $$50$$ $$mA.$$ The torque on the coil is

A moving iron ammeter produces a full scale torque of $$240$$ $$\,\mu Nm$$ with a deflection of $${120^ \circ }$$ at a current of $$10$$ $$A$$. The rate of change of self inductance $$\left( {\mu H/radian} \right)$$ of the instrument at full scale is