Working Scientifically

Question 1

Define “Hazard”

Answer 1

Something that can cause harm

Question 2

Define “Risk”

Answer 2

A chance that a hazard will cause somebody harm.

Question 3

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

Answer 3

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

Question 3

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

Answer 3

Tie hair back, tuck in ties and shirts.

Question 4

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

Answer 4

Open windows to allow movement of air in and out

Question 5

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

Answer 5

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

Question 6

What is an independent variable?

Answer 6

Something that you change during the experiment

Question 7

What is a dependant variable?

Answer 7

The variable being tested or measured during the experiment.

Question 7

Define accuracy

Answer 7

How close the measurement is to the true value

Question 8

What is a control variable?

Answer 8

The variable that is kept the same throughout the experiment

Question 9

Define calibration

Answer 9

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)

Question 10

Define data

Answer 10

Information, either qualitative or quantitative that has been collected

Question 11

Define error

Answer 11

mistake

Question 12

Define measurement error

Answer 12

The difference between a measured value and the true value

Question 13

Define anomalies

Answer 13

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

Question 14

What does a random error do?

Answer 14

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

Question 15

When are random errors made?

Answer 15

Whenever any measurement is made. They cannot be corrected.

Question 16

How do you reduce the effect of random error?

Answer 16

Making more measurements and calculating a new mean

Question 17

What do systematic errors cause?

Answer 17

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

Question 17

Define systematic error

Answer 17

An error caused by misreading a measurement

Question 18

List some sources of systematic error

Answer 18

The environment, methods of observation, instruments used.

Question 19

Define zero error

Answer 19

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

Question 20

What type of uncertainty can a zero error result in?

Answer 20

Systematic uncertainty

Question 21

Define evidence

Answer 21

Data which has been shown to be valid

Question 22

Define a fair test

Answer 22

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

Question 23

Define a hypothesis

Answer 23

A proposal intended to explain certain facts or observations

Question 24

Define interval

Answer 24

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)

Question 25

Define precision

Answer 25

How close measurements are to each other

Question 26

What is the difference between precision and accuracy?

Answer 26

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

Question 27

Define prediction

Answer 27

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

Question 28

Define range

Answer 28

The maximum and minimum values

Question 29

What makes an experiment reproducible

Answer 29

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

Question 29

What makes an experiment repeatable

Answer 29

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

Question 30

Repeatable vs Reproducible

Answer 30

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

Question 31

Define resolution

Answer 31

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

Question 32

What is a sketch graph?

Answer 32

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

Question 32

Define true value

Answer 32

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

Question 33

Define uncertainty

Answer 33

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

Question 34

How can you find the uncertainty?

Answer 34

Find the range and divide it by 2.

Question 35

How do you calculate percentage uncertainty?

Answer 35

Uncertainty/Volume measured x100

Question 36

Systematic error vs random error

Answer 36

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

Question 37

Zero error vs systematic error

Answer 37

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