The deflection in a moving coil galvanometer is reduced to half when it is shunted with a $40 \Omega$ coil. The resistance of the galvanometer is (in $\Omega$)

Fill in the blanks: The possible value of the resistance of an ammeter is ...... and the possible value of the resistance of a voltmeter is ..... . (more,less)

Give the unit of shunt.

Define the function of the small cylinder in the construction of a galvanometer.

To convert a galvanometer into an ammeter,a shunt of $0.01\,\Omega$ is used. The resistance of the galvanometer coil is $50\,\Omega$ and its maximum deflection current is $20\,mA$. The range of the ammeter is:

Two moving coil galvanometers $A$ and $B$ having identical springs are placed in magnetic fields of $0.25 \ T$ and $0.5 \ T$ respectively. If the number of turns in $A$ and $B$ are respectively $36$ and $48$,and the areas of the coils $A$ and $B$ are $2.4 \times 10^{-3} \ m^2$ and $4.8 \times 10^{-3} \ m^2$ respectively,then the ratio of the current sensitivities of the galvanometers $A$ and $B$ is