Multirange Ammeter magnitudes homework

[parm09]

Can someone please help me out with this problem? I am not sure if what I am doing

The question:

The resistance of the moving coil of the galvanometer G in Fig. 26.73 is 48.0 ohms, and the galvanometer deflects full scale with a current of 0.0200 A. When the meter is connected to the circuit being measured, one connection is made to the post marked + and the other to the post marked with the desired current range. Find the magnitudes of the resistances R1, R2, and R3 that are required to convert the galvanometer to a multirange ammeter deflecting full scale with currents of 10.0 A, 1.00 A, and 0.100 A.

The picture:

I assume we are looking for the shunt resistor in each case?
Rsh=(Ifs)*(Rc)/(Ia-Ifs)
[

 

[willem2]

I assume we are looking for the shunt resistor in each case?
Rsh=(Ifs)*(Rc)/(Ia-Ifs)
[

yes. There are also resistance(s) in series with the meter.
for the 10 A case R2+R3 increase the internal resistance of the galvanometer and R1
is the shunt resistance

 

[tomcue]

Ifs = full scale current of galvanometer, Ia = desired current range, Rc = resistance of galvanometer]

To convert the galvanometer to a multirange ammeter, we need to add shunt resistors in parallel with the galvanometer. The equation you provided is correct for finding the value of the shunt resistor. We need to use this equation for each desired current range.

For 10.0 A range:

Rsh = (0.0200 A * 48.0 ohms) / (10.0 A - 0.0200 A) = 0.096 ohms

Therefore, R1 = 0.096 ohms.

For 1.00 A range:

Rsh = (0.0200 A * 48.0 ohms) / (1.00 A - 0.0200 A) = 0.960 ohms

Therefore, R2 = 0.960 ohms.

For 0.100 A range:

Rsh = (0.0200 A * 48.0 ohms) / (0.100 A - 0.0200 A) = 9.60 ohms

Therefore, R3 = 9.60 ohms.

It is important to note that the shunt resistors must be connected in parallel with the galvanometer, with one end connected to the + post and the other end connected to the post marked with the desired current range. This will ensure that the galvanometer will deflect full scale for each desired current range.