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Units and Measurement
Question
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A student measured the diameter of a small steel ball using a screw gauge of least count 0.001 cm. The main scale reading is 5 mm and zero of circular scale division coincides with 25 divisions above the reference level. If screw gauge has a zero error of –0.004 cm, the correct diameter of the ball is

  • 0.521 cm

  • 0.525 cm

  • 0.529 cm

  • 0.053

Answer

C.

0.529 cm

Diameter of the ball

= MSR + CSR x (least count) - zero error

 = 0.5 cm + 25 x 0.001 - (-0.004)

= 0.5 + 0.025 + 0.004

= 0.529 cm

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Some More Questions From Units and Measurement Chapter

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