Working Scientifically Flashcards
What is a hazard?
Something that could potentially cause harm
Name 2 safety procedures one should take when working with sulfuric acid
Wear gloves and safety goggles
Name a safety procedure one should take when working with a Busen Burner
Put it on a heat proof mat (reduce risk of starting a fire)
What do you use a hypothesis for?
To make a prediction
What are investigations used for?
To see if there’s patterns or relationships between 2 variables
Evidence needs to be _________, ________ and ______
Repeatable, Reproducible and Valid
What is meant by repeatable?
If same person does an experiment using same method & equipment = get similar results
What is meant by reproducible?
If someone else does experiment, or different method or equipment used = similar results
What is meant by valid results?
- Both repeatable and reproducible AND answer original question
- Come from fair experiments
Data that’s repeatable and reproducible is _____
reliable
____ the Sample Size the Better
Bigger
Why should a sample size be big (name 2 reasons)
- Sample should represent whole population
- Smaller samples = harder to spot anomalies
Why do samples not include everyone? (name 2 reasons)
Would take too long and cost too much
How do you get a fair test?
By controlling variables
What is an independent variable?
Variable you change
What is a dependent variable?
Variable you measure when you change independent variable
What are control variables?
Variables you keep the same
Measuring equipment needs to be _____ enough
sensitive
What is meant by resolution?
Smallest change a measuring instrument can detect
How can you calibrate equipment?
By measuring known value
e.g. placing a thermometer in melting ice to see whether it reads zero
Data should be ____, _____, _____ and _____
Repeatable, Reproducible, Accurate and Precise
What is meant by accurate?
Results are really close to true answer/value
Why is counting bubbles not very accurate? (give 2 reasons)
∵ you might miss some bubbles or they might have different volumes
What is more accurate than counting bubbles?
Measure vol. of gas using gas syringe
How can you check the repeatability of your results?
By repeating readings to check results are similar
How can you check the reproducibility of your results?
Take 2nd set of readings with another instrument or different observer
What are precise results?
Data really close to mean of your repeated results i.e. not spread out
How can you increase the precision of your results?
Alter experiment - use a smaller scale
Why might results vary?
Due to random errors
What are random errors?
Unpredictable differences
Give an example of random error
e.g. human errors in measuring
How can you reduce the effect of random errors on your results?
By repeat readings & finding the mean = make your results more precise + accurate (if there’s no systematic error)
What is a systematic error?
Measurement wrong by same amount every time
How can you fix a systematic error?
Use a different technique or a different set of equipment
What is a measurement error?
Difference between measured value and true value
What is a zero error?
Systematic error caused by using equipment that isn’t zeroed properly
What are anomalies?
Results that don’t fit trend/pattern, away from line of best fit
What do headings in tables need to include?
Units
When calculating mean, what do you do if you have an anomalous result?
Ignore it
When doing calculations, what should you round your answer to?
Round the answer to lowest number of significant figures given
When do you draw a bar chart?
Independent variable = categoric or discrete (e.g. data counted in chucks, no in-between value = shoe sizes)
When do you draw a line graph?
Both variables = continuous data
How do you calculate rates from a graph?
How do you find the rate at any point on a curved graph?
By drawing a tangent i.e. straight line that touches a single point a curve
What’s the mutilple of unit for tera (T)?
1012
What’s the mutilple of unit for giga (G)?
109
What’s the mutilple of unit for mega (M)?
million = 106
What’s the mutilple of unit for kilo (k)?
1000
What’s the mutilple of unit for deci (d)?
0.1
What’s the mutilple of unit for centi (c)?
0.01
What’s the mutilple of unit for milli (m)?
0.001
What’s the mutilple of unit for micro (µ)?
10-6
What’s the mutilple of unit for nano (n)?
10-9
What’s a conversion factor?
no. of times the smaller unit goes into large unit
How do you get from a bigger unit to smaller unit?
× by conversion factor
How do you get from a smaller unit to bigger unit?
÷ by conversion factor
What is uncertainty?
Interval within which the true value can be expected to lie
What is uncertainty? (simplier definition)
Amount of error your measurements might have
When you repeat a measurement you get a different figure due to random error, what does this mean?
Means each result has some uncertainty to it
Why do measurements you make have uncertainty?
Due to limits in resolution
Larger the range = …
less precise your results are & more uncertainty
How can you reduce uncertainty?
By measuring a greater amount
How do you calculate uncertainty?
Correlation ____ ____ mean Cause
DOES NOT
Name 3 possible reasons for a correlation
- Chance
- Linked by 3rd variable
- Cause
Suggest 3 general changes to a method to improve quality of results
- Increasing the no. of measurements you took
- Changing the way you controlled a variable
- Taking more measurements at narrower intervals (= more accurate result)
Define Evidence
Data that’s valid
Define Hypothesis
Proposal intended to explain certain fact or observation
Define Fair Test
In which only independent variable has allowed to affect the dependent variable
Define Valid
- Free of error
- Suitability of experiment to give accurate results
Define Interval
Quantity between readings
Define True value
Ideal measurement
Define Data
Information = qualitative or quantitative
Define Quantitative
Numbers
Define Qualitative
Verbally done (words)
Define Calibration
Marking a scale on a measuring instrument
Define Prediction
State/suggest what will happen
