What should be the properties of standard resistances?

What should be the properties of a thermometric substance?

What should be the properties of the material for the selection of potentiometer wire ?

What should be the properties of the medium for producing sound waves ?

What should be the properties of the medium for producing sound waves ?

What should be the properties of a liquid to satisfy Bernoulli's theorem ?

What should be the properties of a liquid to satisfy Bernoulli's theorem?

What should be the value of unknown resistance R so that equivalent resistance between P and Q is also R ?

(A): Material used in the construction of a standard resistance is constantan or manganin. (R): Temperature coefficient of Resistance constantan is very small.

What should be the resistance of an ideal ammeter ?