An ammeter and a milliammeter are converted from identical galvanometers. Which one has smaller resistance ?

Options

A. Ammeter
B. Milliammeter
C. Both have equal resistances
D. The resistance of ammeter may be more than or equal to that of milliammeter depending upon its range.

Answer

To determine which device, an ammeter or a milliammeter, has smaller resistance when both are converted from identical galvanometers, we can analyze the relationship between current and resistance.

### Step-by-Step Solution:

1. **Understanding the Devices**:
- An ammeter is designed to measure larger currents (in amperes).
- A milliammeter is designed to measure smaller currents (in milliamperes).

2. **Ohm's Law**:
- According to Ohm's Law, the relationship between voltage (V), current (I), and resistance (R) is given by the formula:
\[ V = I \times R \]
- Rearranging this gives:
\[ I = \frac{V}{R} \]
- This indicates that current (I) is inversely proportional to resistance (R).

3. **Current Ranges**:
- Since an ammeter measures larger currents, it operates at a higher current level compared to a milliammeter, which measures smaller currents.
- Therefore, we can say:
- \( I_{\text{ammeter}} > I_{\text{milliammeter}} \)

4. **Resistance Comparison**:
- From the relationship \( I = \frac{V}{R} \), if the current is higher (as in the case of the ammeter), the resistance must be lower.
- Conversely, if the current is lower (as in the case of the milliammeter), the resistance must be higher.

5. **Conclusion**:
- Since the ammeter has a higher current, it has a lower resistance compared to the milliammeter.
- Therefore, the ammeter has smaller resistance than the milliammeter.

### Final Answer:
The ammeter has smaller resistance than the milliammeter.