Why should an ammeter have a low resistance?

Which of the two, an ammeter or a milliammeter, has a higher resistance and why?

Why should the spring/suspension wire in a moving coil gavanometer have a low torsional constant?

A moving coil galvanometer of resistance 100Omega is used as an ammeter using a resistance 0.1 Omega . The maximum diflection current in the galvanometer is 100 muA . Find the minimum current in the circuit so that the ammeter shows maximum deflection

A battery of e.m.f. 3 volt and internal resistance r is conneted inseries with a resistance of 55 ohm through an ammeter of resistance 1 ohm. The ammeter reads 50 mA. Draw the circuit diagram and calculate the value of r.

Why should we have narrow sources to produce good interference fringes?

The resistance of an ammeter is 13 Omega and its scale is graduated fro a current upto 100 A. After an additional shunt has been connected to this ammeter it becomes possible to measure currents upto 750 A by this meter. The value of shunt resistance is

Draw a circuit diagram of a meter bridge and write the necessary mathematical relation used to determine the value of unknown resistance. Why cannot such arrangement be used for measuring very low resistances?