Uncertainties in the measurements Flashcards Preview

EE10142 Electronic laboratory techniques > Uncertainties in the measurements > Flashcards

Flashcards in Uncertainties in the measurements Deck (18)
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1
Q

Difficulties that can be encountered when taking measurements using a ruler?

A
  1. Zero Offset
  2. Parallax Error
  3. Fidelity of the scale
  4. Calibration
2
Q

Zero Offset of a ruler?

A

the ruler needs to be placed such that the zero mark is as close as possible at the start of the item to be measured

3
Q

Parallax error of a ruler?

A

measure by viewing straight down at the marks

4
Q

Fidelity of the scale of a ruler?

A

are the graduations exactly 1 mm?

5
Q

Calibration of a ruler?

A

what is a true 1 mm?

6
Q

Rules for significant figures in a measurement?

A
  • Rule 1: For numbers less than 1, we count the number of figures between the first non-zero figure and the last figure inclusive.
    • Example: 0.0010306 has five significant figures.
  • Rule 2: For numbers greater than 10 and ending in a zero, we do not count the zero(s).
    • Example: 545000 has three significant figures.
  • Rule 3: For numbers between 1 and 10 and with decimals consider the following example.
    • Example: 6.12 has three significant figures.
7
Q

Rules for calculations with significant figures?

A
  • Rule 1 - When multiplying or dividing numbers: Identify the number in a calculation that is given to the least number of significant figures. Give the result of the calculation to the same number of significant figures.
    • Example: 3.7 x 3.01 = 11.137 As 3.7 has only two significant figures (least), then we should give the answer as 11.
  • Rule 2 - When adding or subtracting numbers: Round the result of the calculation to the same number of decimal places as the number in the calculation given to the least number of decimal places.
    • Example: 11.24 + 13.1 = 24.34 Using rule 2, we should give the answer as 24.3.
8
Q

Types of Error?

A
  • Systematic uncertainties
  • Random uncertainties
9
Q

Examples of Systematic error?

A
  • Constant (offset)
  • Linearity Drift (or gain) – for example, due to temperature or aging effects
  • Cyclic – for example, daytime cycle of temperature
10
Q

Examples of Random Uncertainties?

A
  • Noise
  • Rounding errors
  • Reading errors Interference
  • Power supply variations
11
Q

Graph showing Random Variation on a graph?

A
12
Q

Graph showing Random variation with systematic drift?

A
13
Q

What is the quantization error?

A

The Unavoidable loss of information

14
Q

Graphs showing how Quantised signal compares to original?

A
15
Q

What is the Precision of results?

A

A description of the spread in the results of repeated measurements

16
Q

What is the accuracy of results?

A

A measure of how close results are to the “true” values

17
Q

Using precision on a reuslts graph?

A
18
Q

Using accuracy on a results graph?

A