How to Calculate Shunt Resistance for Converting a Galvanometer to an Ammeter?

[dgresch]

A galvanometer has a full scale current of 0.100 mA and a coil resistance of 50ohmes. In constructing an ammeter of 60mA full scale, what shunt resistnace is needed?I'm lost on this one.

 

[gneill]

This is a common problem type. Try searching the forum for similar examples. In fact, take a look at the bottom of this window under the "Similar Threads" header.

 

[berkeman]

A galvanometer has a full scale current of 0.100 mA and a coil resistance of 50ohmes. In constructing an ammeter of 60mA full scale, what shunt resistnace is needed?


I'm lost on this one.

You want 0.1mA to go through the 50 Ohm coil, and the rest of the 60mA to go through the low-resistance shunt in parallel with the coil. What do you think the Relevant Equations are?

 

[dgresch]

Thanks gneill, I'm new to this and I thought to just post my own thread since I didn't see it on google :P.

 

[rohans]

is the answer 0.083ohm

 

[gneill]

is the answer 0.083ohm

It might be Can you show your work?

 

[rohans]

s=(Ig/(I-Ig))*R
s-required shunt
R-resistance of galvanometer(50)
Ig-full scale deflection current of the galvanometer(0.1)
I-desired current range(60)
just substitute the given data