1 Measurements and their errors Flashcards

1
Q

What are the fundamental (base) units

A
  • Metre (m)
  • kilogram (kg)
  • second (s)
  • Kelvin (K)
  • mole (n)
  • Ampere (A)
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2
Q

What quantities are the fundamental (base) units for

A
  • Length
  • Mass
  • Time
  • Temperature
  • Amount of substance
  • Electrical current
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3
Q

What are SI derived units?

A

Units that consist of the fundamental (base) units

For example: Newtons= kg m s-2

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4
Q

What are the SI prefixes
* kilo (k)
* Mega (M)
* Giga (G)
* Tera (T)
in standard form?

A
  • 103
  • 106
  • 109
  • 1012
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5
Q

What are the SI prefixes
* centi (c)
* milli (m)
* micro (μ)
* nano (n)
* pico (p)
* femto (f)
in standard form?

A
  • 10-2
  • 10-3
  • 10-6
  • 10-9
  • 10-12
  • 10-15
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6
Q

What is 1 eV in J?

A

1.6*10-19 J

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7
Q

What is 1 J in eV?

A

6.25*1018 eV

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8
Q

What is 1 kW h in J?

A

3.6*106 J

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9
Q

What is 1 J in kW h?

A

2.78*10-7 kW h

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10
Q

Define random error.

A

An error introduced by variables which you cannot control.

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11
Q

Define systematic error.

A

An error introduced by the experimental apparatus or method.

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12
Q

Define precision.

A

Repeated measurements that are bery similar to the calculated mean value.

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13
Q

Define repeatability.

A

If the experiment can be repeated multiple times and get the same result.

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14
Q

Define reproducibility.

A

If someone else can recreate the experiment using different equipment or methods and get the same result.

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15
Q

Define resolution.

A

The smallest change that can be measured using the equipment that gives a readable change in the reading.

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16
Q

Define accuracy.

A

How close a measurement or answer is to the true value.

17
Q

Define uncertainty.

A

The range within which you would expect the true value to lie.

18
Q

Define absolute uncertainty.

A

Is the uncertainty of a measurement given as a fixed quantity.

19
Q

Define fractional uncertainty.

A

Is the uncertainty given as a fraction of the measurement taken.

20
Q

Define percentage uncertainty

A

Is the uncertainty given as a percentage of the measurement.

21
Q

How would you represent uncertainty in the final answer for a quantity?

A

(Result ± uncertainty) units

22
Q

How would you combine absolute uncertainties?

A

When you add or subtract quantities, you add the absolute uncertainties for each value

23
Q

How would you combine percentage uncertainties?

A

When you multiply or divide quantities, you add the percentage uncertainties for each value

When a measurement is raised by a power n, the percentage uncertainty is multiplied by n.

24
Q

How would you represent uncertainty in a data point in a graph?

A

With error bars.

25
How would you determine the uncertainty in the gradient of a striaght-line graph?
* Draw lines of best fit which have the maximum and minimum possible gradients for the data. * Uncertainty is the difference between the best and worst gradients. | Both should go through all of the error bars.
26
How would you determine the uncertainty in the intercept of a striaght-line graph?
* Draw lines of best fit which have the maximum and minimum possible intercepts for the data. * Uncertainty is the difference between the best and worst intercepts. | Both should go through all of the error bars.
27
What is an order of magnitude?
Powers of ten which describe the size of an object, and which can also be used to compare the sizes of objects.