The least count of vernier callipers is `0.1 mm`. The main scale reading before the zero of the vernier scale is `10` and the zeroth division of the vernier scale coincides with the main scale division. Given that each main scale division is `1mm`. The measured value should be expressed as

Options

A. `1 cm`
B. `2 cm`
C. `0.5 cm`
D. `0.1 cm`

Explanation

To solve the problem step by step, we will follow the given information about the vernier calipers and perform the necessary calculations.

### Step 1: Identify the Main Scale Reading (MSR)
The problem states that the main scale reading before the zero of the vernier scale is 10. Since each main scale division is 1 mm, the main scale reading (MSR) is:
\[ \text{MSR} = 10 \, \text{mm} \]

### Step 2: Identify the Vernier Scale Reading (VSR)
The zeroth division of the vernier scale coincides with the main scale division. This means that the reading on the vernier scale (VSR) is:
\[ \text{VSR} = 0 \times 0.1 \, \text{mm} = 0 \, \text{mm} \]

### Step 3: Calculate the Zero Correction (ZC)
Since the zeroth division of the vernier scale coincides with the main scale, there is no zero error. Therefore, the zero correction (ZC) is:
\[ \text{ZC} = 0 \, \text{mm} \]

### Step 4: Calculate the True Reading (TR)
The true reading can be calculated using the formula:
\[ \text{TR} = \text{MSR} + \text{VSR} - \text{ZC} \]
Substituting the values we have:
\[ \text{TR} = 10 \, \text{mm} + 0 \, \text{mm} - 0 \, \text{mm} = 10 \, \text{mm} \]

### Step 5: Convert the True Reading to Centimeters
To express the measured value in centimeters, we convert millimeters to centimeters:
\[ \text{TR in cm} = \frac{10 \, \text{mm}}{10} = 1 \, \text{cm} \]

### Step 6: Express the Final Answer
Since the problem asks for the measured value to be expressed with one decimal place, we write:
\[ \text{Final Answer} = 1.0 \, \text{cm} \]

### Summary
The measured value should be expressed as **1.0 cm**.

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