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One Angstrom is equal to:

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Important Questions on Units and Measurements

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Physics>Mechanics>Units and Measurements>Measurement of Length

A specially designed Vernier caliper has the main scale least count of

1 mm

. On the Vernier scale, there are 10 equal divisions and they match with 11 main scale divisions. Then, the least count of the Vernier caliper is:

MEDIUM

Physics>Mechanics>Units and Measurements>Measurement of Length

If the screw on a screw-gauge is given six rotations, it moves by

3 mm

on the main scale. If there are

50

divisions on the circular scale the least count of the screw gauge is:

EASY

Physics>Mechanics>Units and Measurements>Measurement of Length

A screw gauge has

50

divisions on its circular scale. The circular scale is

4

units ahead of the pitch scale marking, prior to use. Upon one complete rotation of the circular scale, a displacement of

0.5 mm

is noticed on the pitch scale. The nature of zero error involved and the least count of the screw gauge, are respectively:

EASY

Physics>Mechanics>Units and Measurements>Measurement of Length

In a screw gauge,

5

complete rotations of the screw cause it to move a linear distance of

0.25 cm

. There are

100

circular scale divisions. The thickness of a wire measured by this screw gauge gives a reading of

4

main scale divisions and

30

circular scale divisions. Assuming negligible error, the thickness of the wire is

MEDIUM

Physics>Mechanics>Units and Measurements>Measurement of Length

Diameter of a steel ball is measured using a Vernier calipers which has divisions of 0.1 cm on its main scale (MS) and 10 divisions of its Vernier scale (VS) match 9 divisions on the main scale. Three such measurements for a ball are given as:

S.No.	MS (cm)	VS divisions
1.	0.5	8
2.	0.5	4
3.	0.5	6

If the zero error is - 0.03 cm, then mean corrected diameter is:

MEDIUM

Physics>Mechanics>Units and Measurements>Measurement of Length

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

25^{t h}

division of circular scale coincides with reference line. If screw gauge has a zero error of

- 0.004 cm

, the correct diameter of the ball is

EASY

Physics>Mechanics>Units and Measurements>Measurement of Length

The least count of the main scale of a vernier calipers is

1 mm

. Its vernier scale is divided into

10

divisions and coincide with

9

divisions of the main scale. When jaws are touching each other, the

7^{th}

division of the vernier scale coincides with a division of the main scale and the zero of vernier scale is lying right side of the zero of the main scale. When this vernier is used to measure the length of the cylinder the zero of the vernier scale between

3.1 cm

and

3.2 cm

and

4^{th}

VSD coincides with the main scale division. The length of the cylinder is (VSD is vernier scale division)

EASY

Physics>Mechanics>Units and Measurements>Measurement of Length

The nearest star to our solar system is

4.3

light years away. The distance of this star in Parsec is (Mean distance between the earth and the sun

= 1.5 \times 10^{11} m

and one light year

= 9.46 \times 10^{15} m)

HARD

Physics>Mechanics>Units and Measurements>Measurement of Length

The diameter of a cylinder is measured using a vernier callipers with no zero error. It is found that the zero of the vernier scale lies between

5.10 cm

and

5.15 cm

of the main scale. The vernier scale has

50

divisions equivalent to

2.45 cm

. The

24^{th}

division of the vernier scale exactly coincides with one of the main scale divisions. The diameter of the cylinder is,

HARD

Physics>Mechanics>Units and Measurements>Measurement of Length

Consider a Vernier calipers in which each

1 cm

on the main scale is divided into

8

equal divisions and a screw gauge with

100

divisions on its circular scale. In the Vernier calipers,

5

divisions of the Vernier scale coincide with

4

divisions on the main scale and in the screw gauge, one complete rotation of the circular scale moves it by two divisions on the linear scale. Then:

EASY

Physics>Mechanics>Units and Measurements>Measurement of Length

A screw gauge has least count of

0.01 mm

and there are

50

divisions in its circular scale. The pitch of the screw gauge is:

MEDIUM

Physics>Mechanics>Units and Measurements>Measurement of Length

The least count of the main scale of a screw gauge is

1 mm .

The minimum number of divisions on its circular scale required to measure

5 μm

diameter of a wire is:

EASY

Physics>Mechanics>Units and Measurements>Measurement of Length

The dimension of light year

MEDIUM

Physics>Mechanics>Units and Measurements>Measurement of Length

The pitch of the screw gauge is

1 mm

and there are

100

divisions on the circular scale. When nothing is put in between the jaws, the zero of the circular scale lies

8

divisions below the reference line. When a wire is placed between the jaws, the first linear scale division is clearly visible while

72^{nd}

division on circular scale coincides with the reference line. The radius of the wire is

MEDIUM

Physics>Mechanics>Units and Measurements>Measurement of Length

A screw gauge with a pitch of

0.5 mm

and a circular scale with

50

divisions is used to measure the thickness of a thin sheet of aluminium. Before starting the measurement, it is found that when the two jaws of the screw gauge are brought in contact, the

45^{t h}

division coincides with the main scale line and that the zero of the main scale is barely visible. What is the thickness of the sheet if the main scale reading is

0 .5 mm

and the

25^{t h}

division coincides with the main scale line?

MEDIUM

Physics>Mechanics>Units and Measurements>Measurement of Length

The pitch and the number of divisions, on the circular scale, for a given screw gauge are

0.5 mm

and

100

respectively. When the screw gauge is fully tightened without any object, the zero of its circular scale lies

3

divisions below the mean line.

The readings of the main scale and the circular scale, for a thin sheet, are

5 .5 mm

and

48

respectively, the thickness of this sheet is:

HARD

Physics>Mechanics>Units and Measurements>Measurement of Length

There are two vernier calipers both of which have $1 cm$ divided into $10$ equal divisions on the main scale. The Vernier scale of one of the calipers $(C_{1})$ has $10$ equal divisions that correspond to $9$ main scale divisions. The Vernier scale of the other caliper $(C_{2})$ has $10$ equal divisions that correspond to $11$ main scale divisions. The readings of the two calipers are shown in the figure. The measured values (in $cm$ ) by calipers $C_{1}$ and $C_{2}$ respectively, are

Question Image

EASY

Physics>Mechanics>Units and Measurements>Measurement of Length

A SONAR (sound navigation and ranging) uses ultrasonic waves to detect and locate objects under water. In a submarine equipped with a SONAR, the time delay between generation of a probe wave and the reception of its echo after reflection from an enemy submarine is found to be

77.0 s

. What is the distance of the enemy submarine? (Speed of sound in water

= 1450 m s^{- 1}

EASY

Physics>Mechanics>Units and Measurements>Measurement of Length

A new unit of length is chosen such that the speed of light in vacuum is unity. What is the distance between the sun and the earth in terms of the new unit if light takes

8

minutes and

20

seconds to cover this distance?

EASY

Physics>Mechanics>Units and Measurements>Measurement of Length

The farthest objects in our Universe discovered by modern astronomers are so distant that light emitted by them takes billions of years to reach the Earth. These objects (known as quasars) have many puzzling features, which have not yet been satisfactorily explained. What is the distance in

km

of a quasar from which light takes

3.0

billion years to reach us?

One Angstrom is equal to:

Important Questions on Units and Measurements

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