13 - MEASUREMENT OF LENGTH

Question 1

is the process of comparing an unknown quantity with a known quantity.

Answer 1

Measurement

Question 2

Because of human and mechanical limitations, every measurement is an ___________.

Answer 2

approximation

Question 3

__________ is a way of describing how close a measured or calculated quantity is to that of the actual (true) quantity it represents.

Answer 3

Accuracy

Question 4

_________ describes to which further measurements or calculations show the same or similar results.

Answer 4

Precision

Question 5

Precision is also called

Answer 5

reproducibility or repeatability

Question 6

A measurement system is called valid if it is both

Answer 6

accurate and precise

Question 7

A scientific measurement consists of a _________ and a ___________.

Answer 7

number
dimensional unit

Question 8

Since the ________ is generally used in scientific work, all the instruments provided in these illustrations have a scale graduated in _________.

Answer 8

metric system
metric units

Question 9

3 instruments used

Answer 9

Vernier Caliper
Micrometer Caliper
Ruler

Question 10

The ________ of the vernier caliper is an auxiliary scale which enables one to exactly determine some fractional part of a division on a fixed scale on which it is attached

Answer 10

vernier scale

Question 11

When the zero line of the vernier scale coincides on any line on the fixed scale divisions, then n divisions of the vernier scale will correspond to n-1 divisions on the fixed scale.

Answer 11

nD = (n- 1)S or D = (n-1)S/n

Question 12

__ is the length of the smallest fixed scale division
__ is the length of the smallest vernier scale division

Answer 12

S
D

Question 13

The ___________ is the term applied to the smallest value that can be read directly from the vernier scale. It is equal to the difference between the fixed scale division and the vernier scale division:

Answer 13

least count (LC) = S-D = S-([n-1]/n)S = S/n

Question 14

is an instrument for determining the distance between two surfaces and for indicating the value of the distance by the use of an accurate pitched screw

Answer 14

micrometer caliper

Question 15

It measures length by translating the distance into revolutions and fractions of revolution of a known pitch.

Answer 15

micrometer caliper

Question 16

To record these revolutions, a ________ is cut lengthwise on the sleeve with the short graduation lines cut perpendicular to it each 0.5 mm apart. Graduation lines touching the reference line are 1 mm apart.

Answer 16

reference line

Question 17

is an instrument consisting of a smooth straight edge
strip of a material with marked off units. It is used to measure the distance between two points.

Answer 17

ruler

Question 18

The micrometer caliper in the measurement set has a pitch of _________. This means that the screw advances this much mm when turned through one revolution. Fractional revolutions of the screw are indicated by the graduation on the ________. The scale around the circumference of the thimble is divided into _____ parts. Each division represents 1/50 of a revolution. When the thimble is turned through one division, the screw advances 1/50 of the pitch, i.e. 1/50 of 0.5 mm or 0.01 mm.

Answer 18

0.5 mm
circumference of the thimble
50

Question 19

CAUTION: the micrometer caliper measurement limit is _______. Measurements beyond this limit may damage the device. Just put N/A to any measurements beyond this.

Answer 19

2.58 cm