Area of the cross-section of a wire is measured using a screw gauge. The pitch of the main scale is $0.5 \text{ mm}$. The circular scale has $100$ divisions and for one full rotation of the circular scale, the main scale shifts by two divisions. The measured readings are listed below.
Measurement conditionMain scale readingCircular scale reading
Two arms of gauge touching each other without wire$0$ division$4$ division
Attempt-$1$: With wire$4$ division$20$ division
Attempt-$2$: With wire$4$ division$16$ division

What are the diameter and cross-sectional area of the wire measured using the screw gauge?

  • A
    $2.22 \pm 0.02 \text{ mm}, \pi(1.23 \pm 0.02) \text{ mm}^2$
  • B
    $2.22 \pm 0.01 \text{ mm}, \pi(1.23 \pm 0.01) \text{ mm}^2$
  • C
    $2.14 \pm 0.02 \text{ mm}, \pi(1.14 \pm 0.02) \text{ mm}^2$
  • D
    $2.14 \pm 0.01 \text{ mm}, \pi(1.14 \pm 0.01) \text{ mm}^2$

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Similar Questions

In a screw gauge,the zero of the circular scale lies $3$ divisions above the horizontal pitch line when their metallic studs are brought in contact. Using this instrument,the thickness of a sheet is measured. If the pitch scale reading is $1 \ mm$ and the circular scale reading is $51$,then the correct thickness of the sheet is . . . . . . $mm$. [Assume least count is $0.01 \ mm$]

Given below are two statements: one is labelled as Assertion $(A)$ and the other is labelled as Reason $(R)$.
Assertion $(A)$: In a Vernier calliper,if a positive zero error exists,then while taking measurements,the reading taken will be more than the actual reading.
Reason $(R)$: The zero error in a Vernier calliper might have happened due to a manufacturing defect or due to rough handling.
In the light of the above statements,choose the correct answer from the options given below:

In an experiment with Vernier callipers of least count $0.1\,mm$,when two jaws are joined together,the zero of the Vernier scale lies to the right of the zero of the main scale and the $6^{th}$ division of the Vernier scale coincides with a main scale division. While measuring the diameter of a spherical bob,the zero of the Vernier scale lies between $3.2\,cm$ and $3.3\,cm$ marks,and the $4^{th}$ division of the Vernier scale coincides with a main scale division. The diameter of the bob is measured as $.......\,cm$.

The least count of a screw gauge is $0.01 \ mm$. If the pitch is increased by $75\%$ and the number of divisions on the circular scale is reduced by $50\%$,the new least count will be . . . . . . $\times 10^{-3} \ mm$.

$A$ student performs an experiment of measuring the thickness of a slab with a vernier calliper whose $50$ divisions of the vernier scale are equal to $49$ divisions of the main scale. He noted that the zero of the vernier scale is between $7.00 \; cm$ and $7.05 \; cm$ mark of the main scale and the $23^{rd}$ division of the vernier scale exactly coincides with the main scale. The measured value of the thickness of the given slab using the calliper will be (in $; cm$)

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