2.1.3 Systematic Errors and Random Errors

Question 1

Define ‘error.’

Answer 1

1. Parallax error;
2. Systematic error;
3. Human error;
4. Zero error;
5. The difference between a computed value or a measured value and a true or theoretically correct value.
6. Random error;

Question 2

What are random errors? What do they look like on graphs?

Answer 2

1. Errors in experimental measurements;
2. Caused by unknown and unpredictable changes in environment / instruments during an experiment.
   - On graphs:
3. Scattered measurements above and below the true value when the measurement is repeated.
4. They are results which are close but not identical.

Question 3

What is a human error?

Answer 3

1. A ‘one-off’ because of a simple mistake in reading or recording a value.
2. Easy to spot errors, because they are wildly different from other repeated values.
3. Human errors are easier to spot, as only one result is affected, and they are bigger errors vs random fluctuation errors.

Question 4

Produce a comparison of random errors and human errors.

Answer 4

1. Different causes - random errors are due to smaller changes in environmental conditions, human errors are just mistakes when an experimenter misreads a value.

Question 5

Produce examples of random error.

Answer 5

1. Temperature changes;
2. Fluctuations in light levels;
3. Power surge;
4. Variable heating in circuits;
5. An unexpectedly large extension of metal wire due to a fault in its structure;
   These would all CONSTITUTE as random errors.

Question 6

Why would one, and how would one reduce error?

Answer 6

1. They would avoid error by repeating results (not always necessary) and calculating a mean.
2. Otherwise, it will lead to an incorrect conclusion, value or theory being produced.

Question 7

Produce examples of human errors.

Answer 7

1. Equipment read wrongly;
2. Result recorded wrongly;
3. Lab partner may have stated incorrectly;

Question 8

What do random errors cause that systematic errors do not?

Answer 8

Anomalous results.

Question 9

Define systematic error.

Answer 9

An error that does not happen by chance, but instead is introduced by an inaccuracy in the apparatus or its use by the person conducting the INVESTIGATION. This error tends to shift all of the measurements in the same direction, so x value might have to be deducted from all results to adjust them.

Question 10

Define zero error.

Answer 10

A type of systematic error caused when an instrument is not properly calibrated or adjusted, and so gives a non-zero value when the true value is zero.

Question 11

Why would systematic errors occur? Produce two examples.

Answer 11

1. Faulty instruments;

2. Improper use £25

Question 12

Are systematic errors hard to remove?

Answer 12

No, one would just minus or add an adjusting value to shift the results back to their proper position.

Question 13

Define parallax error (two lls).

Answer 13

Caused by reading the scale at the wrong angle, for example when one’s eye is not parallel to the meniscus when using a measuring cylinder.