Working as a physicist

Question 1

What is an accurate result?

Answer 1

One which is close to the true value

Question 2

What is a precise result for repeated data?

Answer 2

One where the range that the repeated data is spread over is small

Question 3

What are repeatable results?

Answer 3

If the experiment was repeated by the same experimenter using the same method and equipment then the same results would be obtained

Question 4

What are valid measurements and what can reduce validity of results?

Answer 4

The measurements measure what they are supposed to be measuring. Not controlling all control variables reduces validity because you won’t be testing the effect of the independent variable alone.

Question 5

What are reproducible results?

Answer 5

If the experiment was repeated by a different experimenter using a different method and different equipment then the same results would be obtained

Question 6

Why is reproducibility a better test of quality than repeatability in terms of systematic error?

Answer 6

Because its less likely that the same systematic errors could affect both methods

Question 7

What is a fair test?

Answer 7

One in which only the independent variable has been allowed to affect the dependent variable

Question 8

What is the resolution of an instrument?

Answer 8

The fineness to which an instrument can be read

Question 9

What is meant by an error?

Answer 9

The difference between your measured value and the true value of whatever you re measuring

Question 10

What is meant by a systematic error?

Answer 10

Errors which are the same every time you repeat the experiment. Readings differ from the true value by a constant amount each time a measurement is made

Question 11

What are 3 potential causes of systematic error?

Answer 11

Environment, methods of observation or instruments used

Question 12

Why are systematic errors hard to spot?

Answer 12

Because they are the same each time

Question 13

Do systematic errors affect accuracy, precision or both?

Answer 13

Affect accuracy but not precision

Question 14

What are 2 ways to reduce systematic errors and how can you correct your results?

Answer 14

Check apparatus at the start of the experiment and conduct the experiment carefully keeping an eye on the environment. Repeat the experiment using a different method or different equipment or compare results with others. Find the value of the systematic error and use it to correct your results.

Question 15

What is meant by a random error and how results vary from measurement to measurement?

Answer 15

One which causes readings to be spread bout the true value: error not the same each time. Results vary in an unpredictable way from measurement to measurement.

Question 16

What are 2 ways to reduce random error in individual measurements and 1 way to reduce random error in calculated results like the mean?

Answer 16

Keep controlled variables exactly the same throughout the experiment. Use apparatus with a better resolution. Do more repeats.

Question 17

Does random error affect accuracy, precision or both and how does this make them easier to spot?

Answer 17

It affects precision and accuracy so is easy to spot because precision leads to a large range of readings.

Question 18

Can random error be corrected?

Answer 18

No because they are not the same each time and are not predictable

Question 19

What is meant by zero error and what kind of error does this lead to?

Answer 19

Instrument doesn’t measure zero when the quantity it is measuring is zero. This leads to systematic error

Question 20

What is an anomaly?

Answer 20

A value which is judged to not be part of variation caused by random error/ uncertainty

Question 21

What is meant by the margin of error?

Answer 21

The maximum difference between your value and the true value

Question 22

What is percentage uncertainty and how do we reduce it?

Answer 22

The uncertainty given as a percentage of the measurement. Reduce it by measuring larger values.

Question 23

What are the 7 base quantities and their units?

Answer 23

Mass(kg)
Length (m)
Time (s)
Current (A)
Temperature (K)
Amount of substance (mol)
Luminous denisty (cd)

Question 24

Name three factors which can influence decisions about science.

Answer 24

Economic factors
Social factors
Environmental factors

Question 25

State how many significant figures calculated values must be given to.

Answer 25

Same number of sig figs as the data value with the fewest sig figs in your calculation

Question 26

If you plot a linear graph, how can you tell your independent and dependent are directly proportional?

Answer 26

Graph will be a straight line through the origin.