Page 1 - 9-phy-1 Measurements
P. 1
1Measurements
Measure the area of cross - section of a solid
cylinder by measuring its diameter with
vernier callipers
Date ________________
Vernier callipers is a device which is generally used to measure length as small
as 1/10th of a millimeter (0.1 mm). It has two scales (i) Main Scale (MS)
(ii) Vernier Scale (VS).
Least Count of the instrument
Least count = Value of smallest division on the main scale (MS)
Number of divisions on the vernier scale (VS)
LC = 1 mm / 10 = 0.1 mm = 0.01 cm
Zero Error
If zero of the main scale does not coincide with the zero of the vernier scale,
when the jaws are closed there is zero error in the instrument. This error may
be positive or negative.
01 01 01
0 5 10 0 5 10 0 5 10
Fig. 1.1.1 (No Zero Error) Fig. 1.1.2 (Positive Zero Error) Fig. 1.1.3 (Negative Zero Error)
Positive Zero Error
If zero of the vernier scale is on the right side of the main scale zero, there is
positive zero error. For example, in Fig. 1.1.2 zero of VS is on the right side of
MS zero and 3rd division of the vernier scale coincides with one of the main scale
division. Multiply this number with the least count to obtain value of zero error.
Positive zero error = 3 ´ LC
= 3 ´ 0.01 cm = 0.03 cm
Negative Zero Error
If zero of the vernier scale is on the left side of the main scale zero, then zero
error is negative. For example, in Fig 1.1.3 zero error is negative and 4th division
of the vernier scale coincides with any division of the main scale. Subtract this
number from the total number of divisions on vernier scale (10–4 = 6). Multiply
the resultant number with least count to obtain the value of negative zero error.
Negative zero error = 6 ´ LC
= 6 ´ 0.01 cm = 0.06 cm
Zero Correction
When the zero error is negative, it is added to the observed reading and is called
1
Measure the area of cross - section of a solid
cylinder by measuring its diameter with
vernier callipers
Date ________________
Vernier callipers is a device which is generally used to measure length as small
as 1/10th of a millimeter (0.1 mm). It has two scales (i) Main Scale (MS)
(ii) Vernier Scale (VS).
Least Count of the instrument
Least count = Value of smallest division on the main scale (MS)
Number of divisions on the vernier scale (VS)
LC = 1 mm / 10 = 0.1 mm = 0.01 cm
Zero Error
If zero of the main scale does not coincide with the zero of the vernier scale,
when the jaws are closed there is zero error in the instrument. This error may
be positive or negative.
01 01 01
0 5 10 0 5 10 0 5 10
Fig. 1.1.1 (No Zero Error) Fig. 1.1.2 (Positive Zero Error) Fig. 1.1.3 (Negative Zero Error)
Positive Zero Error
If zero of the vernier scale is on the right side of the main scale zero, there is
positive zero error. For example, in Fig. 1.1.2 zero of VS is on the right side of
MS zero and 3rd division of the vernier scale coincides with one of the main scale
division. Multiply this number with the least count to obtain value of zero error.
Positive zero error = 3 ´ LC
= 3 ´ 0.01 cm = 0.03 cm
Negative Zero Error
If zero of the vernier scale is on the left side of the main scale zero, then zero
error is negative. For example, in Fig 1.1.3 zero error is negative and 4th division
of the vernier scale coincides with any division of the main scale. Subtract this
number from the total number of divisions on vernier scale (10–4 = 6). Multiply
the resultant number with least count to obtain the value of negative zero error.
Negative zero error = 6 ´ LC
= 6 ´ 0.01 cm = 0.06 cm
Zero Correction
When the zero error is negative, it is added to the observed reading and is called
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