USP_Measurement of Length

What is the SI unit of length?

• Ampere

• Second

• Kilogram

• Meter

What does precision of an instrument refer to?

• The size of the instrument

• The smallest unit it can measure

• The weight of the instrument

• The color of the instrument

What is the precision of a measuring tape: ____ cm

What is the precision of a digital calipers?

• 0.001 mm

• 1 cm

• 0.1 cm

• 0.01 mm

What is the precision of a digital micrometer screw gauge: ____ cm

Which instrument is used to measure the external diameter of thin wires?

What is a parallax error?

• An error due to the wrong positioning of the eyes to the object when taking a measurement

• An error due to the wrong calibration of the instrument

• An error due to the wrong unit of measurement

• An error due to the wrong color of the instrument

What must be perpendicular to the scale to avoid parallax error?

• The person taking the measurement

• The line of sight

• The object being measured

• The instrument

Organize these measurements into the right instrument usage.

Groups:

(a) Measuring tape

,

(b) Metre rule

,

(c) Digital calipers

,

(d) Digital micrometer screw gauge

• Width of window frame

• body hip width

• Circumference of tree trunk

• body height

• depth of test tube

• internal diameter of water bottle

• thickness of a paper

• thickness of a coin

Which instrument is used to measure lengths in the range of 0 - 2.5 cm?

• metre rule

• digital calipers

• digital micrometer screw gauge