Galvanometer → Ammeter & Voltmeter

Conversion via shunts and series resistors.

Concept

Galvanometer → Ammeter & Voltmeter is a foundational idea in this chapter. The defining relationship is:

$S = \frac{I_g R_g}{I - I_g}, \quad R_s = \frac{V - I_g R_g}{I_g}$

Ammeter: low-R shunt in parallel. Voltmeter: high-R in series.

Worked Application

Apply the formula to a typical problem from your textbook. Identify the knowns, plug into the equation, and check that the units work out. Always sanity-check the magnitude before accepting an answer.

Common Confusions

• Confusing the variables in the formula — re-read the symbol definitions in the chapter.
• Forgetting unit conversions (cm vs m, g vs kg).
• Ignoring sign conventions where direction matters.

Key Takeaways

• Master the formula $S = \frac{I_g R_g}{I - I_g}, \quad R_s = \frac{V - I_g R_g}{I_g}$ and one canonical example.
• See the chapter index for full derivations, traps and exam-grade problems.