Question

Which of the following is correct about the adjustable blade?

(a) Adjustable blade is attached to main body

(b) Adjustable blade is capable of rotating freely about the centre

(c) Adjustable blade is capable of rotating freely about the free edge

(d) Adjustable blade is attached to base plate

This question was addressed to me in my homework.

My doubt stems from Vernier and Optical Bevel Protractor in chapter Angular Measurement and Circular Division of Engineering Metrology

Answer 1

Correct answer is (b) Adjustable blade is capable of rotating freely about the centre

The best I can explain: Adjustable blade is attached to the circular plate. It is capable of rotating freely about the centre of the main scale. Main scale is engraved on the main body of the instrument. It can be locked in any position.