Terminology in Practical Physics

Question 1

Validity

Answer 1

A measurement is valid if it measures what it is supposed to be measuring
(Depends on method and instruments used)

Question 2

True Value

Answer 2

The value that would be obtained in an ideal measurement

Question 3

Accuracy

Answer 3

Close to the true value

Influenced by random and systematic errors

Question 4

Precision

Answer 4

The consistency between values obtained by a repeated measurement
(Can be expressed numerically through standard deviation)

Question 5

Resolution

Answer 5

Usually the smallest measuring interval

Smallest change in the quantity being measured that causes a perceptible change in the output being measured

Question 6

Repeatability

Answer 6

A measurement is repeatable when similar results are obtained by the same group using the same method

Question 7

Reproducibility

Answer 7

A measurement is reproducible when similar results are obtained by students from different groups using different methods or apparatus

Question 8

Uncertainty

Answer 8

Any measurement has some uncertainty which comes from variation in the data obtained and is subject to systematic or random effects
Estimated by considering the instruments and method

Question 9

Error

Answer 9

The difference between the measurement result and the true value
Due to systematic and random effects and an error of an unknown size is a source of uncertainty

Question 10

Resolution of a Micrometer

Answer 10

1x10^-5 m

Question 11

Resolution of a Ruler

Answer 11

1x10^-3 m

Question 12

Resolution of a Vernier Calliper

Answer 12

1x10^-4 m

Question 13

How do you measure with a micrometer?

Answer 13

Close jaw to check for zero errors
Measure multiple diameters
Workout the mean