WorksheetsUncertainty in measurement
Total questions: 45
Worksheet time: 40mins
Random errors lead to a lack of:
accuracy in the measurement.
significant digits in the measurement.
precision in the measurement.
gradation of the measuring instrument
length?
3.2 cm
3.12 cm
3 cm
3.219 cm
Systematic errors lead to a lack of:
accuracy in the measurement.
significant digits in the measurement.
precision in the measurement.
gradation of the measuring instrument
Which of these is NOT true for systematic errors?
They arise due to errors in the measuring instruments used.
Repeating the observations or increasing the sample size can eliminate them
They are reproducible inaccuracies that are consistently in the same direction.
They arise from the design of the study.
Repeated measurements of a quantity can reduce the effects of
both random errors and systematic errors
neither random errors nor random errors
random errors
systematic errors
How close a measurement is to the true value is called..
Accuracy
Precision
Significant
Estimate
This bullseye demonstrates...
High Accuracy & High Precision
High Accuracy & Low Precision
Low Accuracy & High Precision
Low Accuracy & Low Precision
The advantages of this are: accuracy in performing manufacturing operations, reduce inspection, an ensure quality products by reducing errors in measurement.
Primary Standards
Secondary Standards
Calibration
Status of Calibration
A measure of consistency or repeatability of measurement.
Precision
Resolution
Sensitivity
Error
Which of these is NOT true for random errors?
They are difficult to detect.
They do not arise from the design of the study.
They are less likely for small sample sizes.
Two students A and B measured the diameter of a wire in mm.
Data A: 1.57, 1.58, 1.43, 1.50, 1.42 Average of data A: 1.50
Data B: 1.60, 1.59, 1.59, 1.60, 1.62 Average of data B: 1.60
Actual diameter is known to be 1.50 mm.
Whose data is more precise?
A, because the values in his data are close to each other
B, because the values in his data are close to each other
A, because the average value is close to the actual value
B, because the average value is close to the actual value
Two students A and B measured the diameter of a wire in mm.
Data A: 1.57, 1.58, 1.43, 1.50, 1.42 Average of data A: 1.50
Data B: 1.60, 1.59, 1.59, 1.60, 1.62 Average of data B: 1.60
Actual diameter is known to be 1.50 mm.
Whose data is more accurate?
A, because the values in his data are close to each other
B, because the values in his data are close to each other
A, because the average value is close to the actual value
B, because the average value is close to the actual value
Which of the following is NOT an example of random error?
Measuring wind velocity depends on the height and time at which a measurement is taken. Multiple readings must be taken and averaged because gusts and changes in direction affect the value.
Readings must be estimated when they fall between marks on a scale or when the thickness of a measurement marking is taken into account.
When taking a volume reading in a flask, you may read the value from a different angle each time.
Measuring length with a metal ruler will give a different result at a cold temperature than at a hot temperature, due to thermal expansion of the material.
Which of the following is NOT an example of systematic error?
Forgetting to tare or zero or calibrate a balance that produces mass measurements that are always "off" by the same amount.
Not reading the meniscus at eye level for a volume measurement. The value will be consistently low or high, depending on whether the reading is taken from above or below the mark.
An improperly calibrated thermometer may give accurate readings within a certain temperature range, but become inaccurate at higher or lower temperatures.
When weighing yourself on a scale, you position yourself slightly differently each time.
A measurement result is considered ________ if it is judged to be close to the true value. It is influenced by random and systematic errors.
Precise
Accurate
An error
Resolution
A quality denoting the closeness of agreement (consistency) between values obtained by repeated measurement. It is influenced by random effects and can be expressed numerically.
Repeatability
Precision
Uncertainty
Resolution
Any measurement will have some ____________. This will come from variation in the data obtained and be subject to systematic or random effects. This can be estimated by considering the instruments and the method and will usually be expressed as a range such as 20 ± 2 °C.
Error
Precision
Reproducibility
Uncertainty
Which result is not accurate but precise?
A
B
C
D
I have read all my burette readings not at eye level but from above
Random error
Systematic error
Misjudging the color of the indicator near the end point
Random error
Systematic error
Using wrong amount of indicator for one of the titration
Random error
Systematic error
Rinsing burette and/or pipette with distilled water
Random error
Systematic error
Not transferring all solid/liquid when preparing samples into a volumetric flask
Random error
Systematic error
Leaking burette
Random error
Systematic error
Not filling burette properly - there is an air lock in the burette stopcock it can block the flow of the titrant
Random error
Systematic error
Losing solution - too vigorous swirling can end in liquid splashing from the titration flask before the end point had been reached.
Random error
Systematic error
Not transferring all the volume - shaken pipette may lose a drop of the solution when it is being moved between flasks
Random error
Systematic error
Using lesser titre volume for average calculations (2 data instead of 3)
Random error
Systematic error
When I used the balanced it didn't actually go to zero each time when I tared it
Random error
Systematic error
There's something stuck in the burette, it's been there for the whole experiment!
Random error
Systematic error
Leaving a filter funnel on the burette
Random error
Systematic error
I just glanced at the burette when taking my readings, for some I was sat down for others I stood up
Random error
Systematic error
When I weighed out the salt, some of it spilt onto the balance pan and didn't actually go into the weighing bottle , during the preparation of primary standard solution.
Random error
Systematic error
You've gone over the etched mark when adding distilled water to your standard solution in a volumetric flask.
Random error
Systematic error
How are random errors minimised?
changing equipment
changing the method
calculating an average
errors can't be minimised
How are systematic errors minimised?
taking an average
changing equipment/method
testing a larger group of people
errors can't be minimised
Taking reading in a burette by not keeping it at the eye level gives rise to
systematic error
random error
True or False?
Repeating a reading never removes the systematic error.
True
False
Olu is testing the effects of three different liquids on plant growth. Olu needs to measure out 19 mL of each liquid for her investigation. Which of the following tools should she use to get the most accurate measurements?
THINK: What tools do we use to measure volume?
A beaker with increments of 20 mL
A beaker with increments of 10 mL
A graduated cylinder with increments of 1 mL
A graduated cylinder with increments of 5 mL
Dennen needs to measure out 3 mL of liquid for an investigation. Which of the following tools would he use for the most accurate measurement?
Which of the following tools will provide the most accurate measurement of the mass of a small object?
Shiloh wanted to measure the length of a plastic spork from the cafeteria. She lined up the spork next to the ruler as shown below and observed the length of the spork. She recorded a length of 9cm.
THINK: What are the three things all scientists do when they measure?
She recorded the wrong units.
She needed to choose a larger ruler.
She used the wrong type of ruler.
She lined up the end of the spork at the wrong place on the ruler.
Miguel wants to use an electric scale to find the mass of a rock. He makes sure there are no objects sitting on the pan of a scale. Miguel turns on the scale, and this is what he sees:
Miguel made a measurement error and his measurement is incorrect. What did Miguel do incorrectly?
Miguel forgot to zero (tare) the scale
Miguel forgot to turn on the scale
Miguel forgot to place the object on the scale
Miguel forgot to read the final measurement on the scale
Kacey needed to measure the amount of liquid in a graduated cylinder. He used a graduated cylinder that measured in milliliters. Kacey found that the volume of the liquid was 25 milliliters.
Unfortunately, Kacey made a measurement error and her measurement is incorrect. What did Kacey do incorrectly?
He looked at the top of the meniscus instead of the bottom of the meniscus.
He used a graduated cylinder instead of a beaker.
He used the wrong units.
He forgot to put an object in the beaker and calculate the amount of displaced water.
