Unit 1: Measurements Measurement of Length. What are we learning today? Instruments used to measure length Instruments used to measure length Accuracy

Unit 1: Unit 1: MeasurementMeasurement

ssMeasurement of LengthMeasurement of Length

What are we learning What are we learning today?today?

Instruments used to measure lengthInstruments used to measure length

Accuracy / PrecisionAccuracy / Precision

ErrorsErrors

Vernier calipers Vernier calipers

Micrometer Screw GaugeMicrometer Screw Gauge

Instruments to measure lengthInstruments to measure length

Measuring tapeMeasuring tape is used to measure the is used to measure the distance a ball thrown.distance a ball thrown.

Metre ruleMetre rule is used to measure the length is used to measure the length and breadth of a table.and breadth of a table.

Vernier calipersVernier calipers is used to measure the is used to measure the diameter of a coin/rod.diameter of a coin/rod.

Micrometer screw gaugeMicrometer screw gauge is used to measure is used to measure the thickness of papers.the thickness of papers.

Accuracy / PrecisionAccuracy / Precision Precision / Precision /

AccuracyAccuracy of an of an instrument is instrument is the the smallestsmallest unit it can unit it can accuratelyaccurately measure. measure.

Accuracy / PrecisionAccuracy / PrecisionInstruments used Instruments used

to measure to measure lengthlength

Precision / Precision / AccuracyAccuracy

Measuring tapeMeasuring tape 0.1 cm0.1 cm

Metre ruleMetre rule 0.1 cm0.1 cm

Vernier calipersVernier calipers 0.01 cm0.01 cm

Micrometer screw Micrometer screw guageguage

0.001 cm / 0.01 mm0.001 cm / 0.01 mm

ErrorsErrors Parallax ErrorParallax Error

HumanHuman

Zero ErrorZero Error InstrumentInstrument

ErrorsErrors To avoid parallax error:To avoid parallax error:

The eye must be positioned The eye must be positioned vertically above the mark on the vertically above the mark on the scalescale..

Several readings and the Several readings and the average must be takenaverage must be taken. .

Vernier CalipersVernier Calipers Vernier calipers consist of a Vernier calipers consist of a

main scalemain scale and a and a sliding sliding vernier scalevernier scale. .

Vernier CalipersVernier Calipers Vernier calipers are used to Vernier calipers are used to

measure measure the internal diameters, the internal diameters, external diameters and depth of an external diameters and depth of an objectobject. .

Vernier CalipersVernier Calipers The procedure of reading a vernier The procedure of reading a vernier

calipers:calipers: Read the main scale opposite the zero Read the main scale opposite the zero

mark of the vernier scale. This will give mark of the vernier scale. This will give value up to one decimal place. value up to one decimal place.

Look out for the vernier mark that Look out for the vernier mark that coincides with the marking on the main coincides with the marking on the main scale. This will give the value for the scale. This will give the value for the second decimal place.second decimal place.

Reading The Vernier CalipersReading The Vernier Calipers

32 0 1

MAIN SCALEMAIN SCALE

VERNIER VERNIER SCALESCALE

Step 1Step 1

Step 2Step 2


Step 1Step 1Step 2Step 2

Step 1:Step 1: Reading = 0.1_ cm Reading = 0.1_ cm

Step 2:Step 2: Reading = Reading = 0.15 cm0.15 cm










Step 1Step 1 Step 2Step 2



Micrometer Screw GaugeMicrometer Screw Gauge

Micrometer screw Micrometer screw gauge is used to gauge is used to measure measure anything anything less than 1 cm and less than 1 cm and is too small for the is too small for the vernier calipers to vernier calipers to measuremeasure. .

Micrometer Screw GaugeMicrometer Screw Gauge The procedure of reading a The procedure of reading a

micrometer screw gauge:micrometer screw gauge: Read the main scale at the edge of the Read the main scale at the edge of the

thimble. This will give value up to one thimble. This will give value up to one decimal place in millimetres. decimal place in millimetres.

The thimble scale has 50 divisions, The thimble scale has 50 divisions, each of which is 0.01 mm. Look out for each of which is 0.01 mm. Look out for the thimble mark that coincides with the thimble mark that coincides with the datum line. This will give the value the datum line. This will give the value for the second decimal place in for the second decimal place in millimetres.millimetres.

Reading The Reading The Micrometer Screw GaugeMicrometer Screw Gauge


Step 1:Step 1: Reading Reading

= 0.2__ cm= 0.2__ cm


= = 0.238 cm0.238 cm




= 0.35_ cm= 0.35_ cm


= = 0.370 cm0.370 cm




= 0.1__ cm= 0.1__ cm


= = 0.104 cm0.104 cm




= 0.15_ cm= 0.15_ cm


= = 0.199 cm0.199 cm

Pop Quiz Pop Quiz #1#11.1. A piece of paper is 0.500 m long, 35.2 A piece of paper is 0.500 m long, 35.2

mm wide and 1.5 mm thick. What is the mm wide and 1.5 mm thick. What is the appropriate instrument for measuring (a) appropriate instrument for measuring (a) the length, (b) width and (c) thickness?the length, (b) width and (c) thickness?

2.2. Which instrument can be used to Which instrument can be used to measure the internal diameter of a measure the internal diameter of a measuring cylinder?measuring cylinder?

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Unit 1: Measurements Measurement of Length. What are we learning today? Instruments used to measure length Instruments used to measure length Accuracy