The Ammeter And The Voltmeter

Step 1: Understanding the Concept:
To convert a galvanometer into an ammeter, a low-resistance wire called a "shunt" is connected in parallel with the galvanometer. The resulting device, the ammeter, has an overall resistance that is the equivalent resistance of the galvanometer and the shunt connected in parallel. An ideal ammeter should have zero resistance.

Step 2: Key Formula or Approach:
When two resistors, (galvanometer resistance) and (shunt resistance), are connected in parallel, their equivalent resistance (resistance of the ammeter) is given by: or, more conveniently for two resistors:

Step 3: Detailed Explanation:
Given data:
Galvanometer resistance, .
Shunt resistance, .
Calculation:
Substitute the values into the formula for parallel equivalent resistance: Rounding to one decimal place, we get 19.3 .

Step 4: Final Answer:
The resistance of the ammeter will be approximately 19.3 .