Four ammeters $$M1, M2, M3$$ and $$M4$$ with the following specifications are available.

A current of $$1$$ $$A$$ is to be measured. To obtain minimum error in the reading, one should select meter

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 of _______.

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