Instruments

A 0-1 Ampere moving iron ammeter has an internal resistance of 50 m$$\Omega $$ and inductance of 0.1 mH. A shunt coil is connected to extend its range to 0-10 Ampere for all operating frequencies. The time constant in mi...

A dc voltage with ripple is given by $$v\left( t \right)\,\,\,\, = \,\,\,\,\left[ {100 + 10\sin \left( {\omega t} \right) - 5\sin \left( {3\omega t} \right)} \right]$$ volts. Measurements of this voltage $$v\left( t \rig...

A ($$0-50$$ $$A$$) moving coil ammeter has a voltage drop of $$0.1$$ $$V$$ across its terminals at full scale deflection. The external shunt resistance (in $$milliohms$$) needed to extend its range to ($$0 – 500$$ $$A$$)...

A periodic waveform observed across a load is represented by $$$V\left( t \right) = \left\{ {\matrix{ {1 + \sin \,\omega t} & {0 \le \omega t < 6\pi } \cr { - 1 + \sin \,\omega t} & {6\pi \le \omega t < 12\pi } \cr } } \...

The dc current flowing in a circuit is measured by two ammeters, one PMMC and another electrodynamometer type, connected in series. The PMMC meter contains 100 turns in the coil, the flux density in the air gap is 0.2 Wb...

An analog voltmeter uses external multiplier settings. With a multiplier setting of $$20\,\,k\Omega ,$$ it reads $$440$$ $$V$$ and with a multiplier setting of $$80$$ $$k\Omega ,$$ it reads $$352$$ $$V.$$ For a multiplie...

An ammeter has a current range of $$0$$-$$5A,$$ and its internal resistance is $$0.2\Omega $$. In order to change the range to $$0$$-$$25$$ $$A$$ we need to add a resistance of

A current of $$ - 8 + 6\sqrt 2 \left( {\sin \,\omega t + {{30}^0}} \right)\,\,A$$ is passed though three meters. They are a center zero $$PMMC$$ meter, true $$r.m.s$$ meter and moving $${\rm I}$$ron instrument. The respe...

A DC ammeter has a resistance of $$0.1$$$$\Omega $$ and its current range is $$0$$ – $$100A.$$ If the range is to be extended to $$0$$ –$$500A,$$ the meter requires the following shunt resistance

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$...

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 t...

A galvanometer with a full scale current of $$10$$ $$mA$$ has a resistance of $$1000$$$$\Omega $$. The multiplying power (the ratio of measured current to galvanometer current) of a $$100$$$$\Omega $$ shunt with this gal...

A Manganin swamping resistance is connected in series with a moving coil ammeter consisting of a milli-ammeter and a suitable shunt in order to

The effect of stray magnetic fields on the actuating torque of a portable instrument is maximum when the operating field of the instrument and the stray fields are

The inductance of a certain moving-iron ammeter is expressed as $$L = 10 + 3\theta - {{{\theta ^2}} \over 4}\mu H,\,\,$$ where $$\,\,\theta \,\,\,$$ is the deflection in radians from the zero position. The control spring...

A $$100$$ $$\mu A$$ ammeter has an internal resistance of $$100\,\Omega $$. For extending its range to measure $$500$$ $$\mu A$$, the shunt required is of resistance (in $$\Omega $$)

Two $$100$$ $$\mu A$$ full scale $$PMMC$$ meters are employed to construct a $$10$$ $$V$$ and a $$100$$ $$V$$ full scale voltmeter. These meters will have figures of merit (sensitivities) as

A current of $$\left[ {2 + \sqrt 2 \sin \left( {314t + 30} \right) + 2\sqrt 2 \cos \left( {952t + 45} \right)} \right]$$ is measured with a thermocouple type. $$5A$$ full scale, class $$1$$ meter. The meter reading would...

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

A dynamometer type wattmeter responds to the

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

For a given frequency, the deflecting torque of an induction ammeter is directly proportional to

The moving coil in a dynamometer wattmeter is connected

The scale of a voltmeter is uniform. Its type is

An advantage of a permanent magnet moving coil instrument is that it is

Two $$100V$$ full scale $$PMMC$$ type D.C voltmeter having figure of merits ($$FOM)$$ of $$10k\Omega /V$$ and $$20k\Omega /V$$ are connected in series. The series combination can be used to measure a maximum dc voltage o...

A $$0$$-$$10$$ $$mA$$ $$PMMC$$ ammeter reads $$4$$ $$mA$$ in a circuit. Its bottom control spring snaps suddenly. The meter will now read nearly

An unshielded moving iron voltmeter is used to measure the voltage in an a.c. circuit. If a stray d.c. magnetic field having a component along the axis of the meter coil appears, the meter reading would be