Practical skills Flashcards

To revise practical skills

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1
Q

When calculating an answer what is the appropriate number of significant figures to give your answer in?

A

The same as the value in the question with less number of significant figures.

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2
Q

State the uncertainty when using vernier callipers

A

0.1 cm

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3
Q

State the uncertainty when using a micrometer

A

0.1 mm

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4
Q

Define repeatable

A

When the person carrying out the experiment obtains similar results

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5
Q

Define reproducible

A

When another group carry out the experiment and obtain a similar pattern in their results

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6
Q

Define resolution

A

The smallest change an instrument can detect or display

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7
Q

Define accurate results

A

When the measured quantity has a value close to the true value

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8
Q

Define precision

A

When repeat readings have a small spread in the data

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9
Q

Define uncertainty

A

How accurately you can take a measurement or an expression of the spread of values taken.

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10
Q

How can you find the uncertainty in a single measurement

A

Your estimate using the precision of the equipment as a guide

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11
Q

How can the uncertainty be calcualted when you have repeat readings?

A

Range / 2

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12
Q

When an equation has addition or subtraction can you add the uncertainty or percentage uncertainty?

A

uncertainty

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13
Q

When an equation has multiplication or division can you add the uncertainty or percentage uncertainty?

A

percentage uncertainty

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14
Q

Define percentage uncertainty stating its equation

A

It is the percentage error in your measurements.

Percentage uncertainty = uncertainty / mean value (x100%)

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15
Q

Explain how you can find the percentage uncertainty in a gradient

A
  1. Find the gradient of the best line of fit.
  2. Draw a worst case LOBT and find its gradient.
  3. Calculate the percentage difference between the two values.
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16
Q

Explain how you can find the percentage uncertainty in an intercept

A
  1. Find the intercept from the best line of fit.
  2. Draw a worst case LOBT and find its intercept.
  3. Calculate the percentage difference between the two values.
17
Q

Define a reading

A

The value is found from a single judgment when using a piece of equipment. e.g. thermometer, measuring cylinder. the uncertainty is given as half the precision

18
Q

Define a measurement

A

The value taken as the difference between the judgement between two values e.g. ruler.

The uncertainty is given as half the precision x by 2

19
Q

Define random error

A

Is an error that is different for every reading. This causes repeat readings to spread around the true value and scatter around the line of best fit

20
Q

Define systematic error

A

The same error on all readings. It will shift all results and gradient up or down.