In an internal micrometer, main scale division is of 0.5 mm and there are 50 divisions in circular scale. The least count of the instrument is-

Options

A. 0.005 mm
B. 0.001 mm
C. 0.05 mm
D. 0.01 mm

Explanation

To find the least count of the internal micrometer, we can follow these steps:

### Step 1: Understand the main scale division (MSD)
The main scale division (MSD) is given as 0.5 mm. This means that each division on the main scale corresponds to 0.5 mm.

### Step 2: Identify the number of divisions on the circular scale (CD)
The circular scale has 50 divisions. This means that when the circular scale completes one full rotation, it is divided into 50 equal parts.

### Step 3: Calculate the least count (LC)
The least count of the instrument can be calculated using the formula:
\[ \text{Least Count (LC)} = \frac{\text{Value of 1 Main Scale Division (MSD)}}{\text{Number of divisions on Circular Scale (CD)}} \]
Substituting the values we have:
\[ \text{LC} = \frac{0.5 \text{ mm}}{50} \]

### Step 4: Perform the calculation
Now, we perform the calculation:
\[ \text{LC} = \frac{0.5}{50} = 0.01 \text{ mm} \]

### Conclusion
The least count of the internal micrometer is 0.01 mm.

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