Question

why can be vernier callipers,screw gauge and
spherometer used in direct methods
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Answer 1

Direct Methods of Measurement

Explanation:

• The vernier calipers, screw gauge, and  spherometer used in direct methods of measurement because they can measure the average lengths which range from few meters to 10^(-5) m.
• There are two methods of measurement- direct and indirect methods.
• The direct method involves the use of-

1. A meter scale
2. Vernier calipers
3. Screw gauge
4. Spherometer

• Beyond the range of length measured by these instruments such as very large astronomical distances and very small atomic sizes can only be measured using the indirect method.
• The indirect method involves-

1. Echo or reflection method
2. Triangulation method
3. Parallax method