To determine the length of the glass block as measured by a vernier caliper, we need to understand how to read the scale correctly. Let's break down the process step-by-step. ### Step-by-Step Explanation 1. **Understanding the Vernier Caliper**: - A vernier caliper consists of a main scale and a sliding vernier scale. The main scale is usually marked in centimeters (cm) and millimeters (mm), while the vernier scale allows for more precise measurements, typically to the nearest 0.01 cm (or 0.1 mm). 2. **Reading the Main Scale**: - First, look at the main scale to find the last whole number before the zero of the vernier scale. This gives you the integer part of the measurement. For example, if the last whole number before the zero of the vernier scale is 1 cm, then you have 1 cm so far. 3. **Reading the Vernier Scale**: - Next, look at the vernier scale to find which line aligns best with any line on the main scale. This aligned line gives you the fractional part of the measurement. For instance, if the 4th line on the vernier scale aligns with a line on the main scale, and each line on the vernier scale represents 0.01 cm, then you add 0.04 cm to your measurement. 4. **Combining the Measurements**: - Combine the readings from the main scale and the vernier scale to get the total length. For example, if the main scale reads 1.6 cm and the vernier scale reads 0.04 cm, the total length would be 1.64 cm. 5. **Final Measurement**: - Based on the image provided (which we cannot see but assume is similar to typical vernier caliper readings), if the main scale reads 1.6 cm and the vernier scale aligns at 0.04 cm, the total length of the glass block would be 1.64 cm. ### Why Option B is Correct - **Correct Option**: The correct answer is **B. 1.64 cm**. This is derived from the combination of the main scale reading and the vernier scale reading as explained above. ### Why Other Options are Incorrect - **Option A (1.63 cm)**: This option is lower than the correct measurement. It may arise from misreading the vernier scale or not accounting for the correct alignment of the lines. - **Option C (1.65 cm)**: This option is slightly higher than the correct measurement. It could be a result of misjudging the alignment of the vernier scale lines, possibly reading one line too high. - **Option D (1.66 cm)**: This option is significantly higher than the correct measurement. It suggests a misunderstanding of the scale or an error in reading the vernier scale. ### Common Pitfalls - **Misreading the Scale**: One of the most common mistakes is misreading the lines on either the main or vernier scale. Always double-check the alignment. - **Forgetting to Add**: Sometimes, students forget to add the readings from the main and vernier scales together, leading to an incorrect total. - **Not Knowing the Scale**: Ensure you know the smallest division on the vernier scale. If it’s 0.01 cm, make sure to read it accurately. ### Revision Summary - **Vernier Caliper Basics**: Understand how to read both the main and vernier scales. - **Measurement Process**: Combine the readings from both scales for the total length. - **Common Errors**: Be aware of misreading and calculation errors. - **Practice**: Regularly practice with different vernier caliper readings to improve accuracy. By following these steps and understanding the reasoning behind the measurements, you can confidently determine the length of objects using a vernier caliper.