To determine the fraction of the main current passing through the galvanometer and the shunt, we can use the concept of parallel resistances, since both the galvanometer and shunt are connected in parallel in an ammeter.
Let's denote:
Rg as the resistance of the galvanometer, which is
90ΩRs as the resistance of the shunt, which is
10ΩIg as the current passing through the galvanometer
Is as the current passing through the shunt
I as the main current passing through the ammeter
According to the parallel circuit rule, the voltage across both the galvanometer and shunt will be the same. So, we have:
Rg⋅Ig=Rs⋅IsMoreover,
I=Ig+Is.
First, express
Is in terms of
Ig :
Is=⋅Ig=⋅Ig=9⋅Ig Substitute this back into the equation for the total current:
I=Ig+Is=Ig+9⋅Ig=10⋅Ig Therefore, the fraction of the main current passing through the galvanometer is:
==And the fraction of the main current passing through the shunt is:
==So, the correct option is:
Option C:
and