Working Scientifically Flashcards

1
Q

Define “Hazard”

A

Something that can cause harm

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2
Q

Define “Risk”

A

A chance that a hazard will cause somebody harm.

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3
Q

What do you do to reduce the risks when using a corrosive acid?

A

Store acid away safely or at least move away from the edge of the bench.

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3
Q

What do you do to reduce the risks when using a flame from a Bunsen burner?

A

Tie hair back, tuck in ties and shirts.

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4
Q

What do you do to reduce the risks caused by the fumes from chemicals?

A

Open windows to allow movement of air in and out

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5
Q

What to do to reduce the hazards when having bags on the floor

A

Store bags under benches safely out of the way and walk carefully around the room.

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6
Q

What is an independent variable?

A

Something that you change during the experiment

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7
Q

What is a dependant variable?

A

The variable being tested or measured during the experiment.

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7
Q

Define accuracy

A

How close the measurement is to the true value

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8
Q

What is a control variable?

A

The variable that is kept the same throughout the experiment

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9
Q

Define calibration

A

Marking a scale in a measuring instrument. (eg, placing a thermometer in melting ice to see whether it reads zero, in order to check if it has been calibrated correctly)

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10
Q

Define data

A

Information, either qualitative or quantitative that has been collected

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11
Q

Define error

A

mistake

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12
Q

Define measurement error

A

The difference between a measured value and the true value

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13
Q

Define anomalies

A

These are values in a set of results which are judged not to be part of the variation caused by random uncertainty.

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14
Q

What does a random error do?

A

Causes readings to be spread about the true value, due to results varying in an unpredictable way from one measurement to the next.

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15
Q

When are random errors made?

A

Whenever any measurement is made. They cannot be corrected.

16
Q

How do you reduce the effect of random error?

A

Making more measurements and calculating a new mean

17
Q

What do systematic errors cause?

A

Cause readings to differ from the true value by a consistent amount each time a measurement is made.

17
Q

Define systematic error

A

An error caused by misreading a measurement

18
Q

List some sources of systematic error

A

The environment, methods of observation, instruments used.

19
Q

Define zero error

A

It is a type of error in which an instrument gives a reading when the true reading at that time is zero

20
Q

What type of uncertainty can a zero error result in?

A

Systematic uncertainty

21
Q

Define evidence

A

Data which has been shown to be valid

22
Q

Define a fair test

A

A test in which only the independent variable has been allowed to affect the dependant variable

23
Q

Define a hypothesis

A

A proposal intended to explain certain facts or observations

24
Q

Define interval

A

The quantity between readings. (eg, a set of 11 readings equally spaced over a distance of 1 meter would give an interval of 10 centimetres)

25
Q

Define precision

A

How close measurements are to each other

26
Q

What is the difference between precision and accuracy?

A

Precision is how close the results are to eachother, accuracy is how close they are to the true value

27
Q

Define prediction

A

A statement suggesting what will happen in the future, based on observation, experience or a hypothesis

28
Q

Define range

A

The maximum and minimum values

29
Q

What makes an experiment reproducible

A

If the investigation is repeated by another person, or by using different equipment or techniques, and the same results are obtained

29
Q

What makes an experiment repeatable

A

If the original experimenter repeats the investigation using the same method and equipment and obtains the same results

30
Q

Repeatable vs Reproducible

A

Repeatable just means you’ll get the same results if you repeat the experiment, reproducible means someone else can repeat it using different equipment or different method and the same results will be obtained

31
Q

Define resolution

A

The smallest change in the quantity being measured of a measuring instrument. (eg a ruler’s resolution is 0.1cm)

32
Q

What is a sketch graph?

A

A line graph that shows the general shape of the relationship between two variables. No points plotted.

32
Q

Define true value

A

The value that would be obtained in an ideal measurement. The actual value.

33
Q

Define uncertainty

A

The interval within which the true value can be expected to lie. (+ or - x.)

34
Q

How can you find the uncertainty?

A

Find the range and divide it by 2.

35
Q

How do you calculate percentage uncertainty?

A

Uncertainty/Volume measured x100

36
Q

Systematic error vs random error

A

Systematic = all the results are wrong due to an outside factor
Random error = one result is wrong

37
Q

Zero error vs systematic error

A

Zero error is in relation to incorrect calibration of equipment which makes the measurement wrong by the same amount each time, systematic error is in relation to an outside factor which makes the measurement wrong by the same amount every time