# 2.2 Making Measurements and Analysing Data Flashcards Preview

## Physics A Level > 2.2 Making Measurements and Analysing Data > Flashcards

Flashcards in 2.2 Making Measurements and Analysing Data Deck (17)
1
Q

What is a systematic (zero) error?

A

The measurements all differ from the true value by a consistent amount

2
Q

What can cause a systematic (zero) error? (2)

A

The way in which a measurement is taken

Faulty measuring devices (wrongly calibrated, etc.)

3
Q

What is a random error?

A

Measurement errors in which the measurements vary unpredictably

4
Q

What can cause a random error? (2)

A

Factors that are not controlled in the experiment

Difficulty in deciding the reading given by the measuring device

5
Q

What is the difference between accuracy and precision? (2)

A

Accuracy is to do with how close a measurement result is to the true value - closer values are more accurate

Precision is to do with how close repeated measurements are to each other - closer values are more precise

6
Q

What is the uncertainty of a measurement?

A

An interval within which the true value is expected to lie

7
Q

What is absolute uncertainty?

A

The +/- value after a measurement as a result of the resolution used or the range of values obtained

8
Q

How is percentage error calculated?

A

% uncertainty = absolute uncertainty / value x 100

9
Q

What is the resolution of a measuring instrument?

A

The smallest change in the measured quantity the instrument can show; e.g. 2 decimal places = +/- 0.01

10
Q

How are errors combined when multiplying or dividing quantities?

A

11
Q

How should a line of best fit be drawn? (2)

A

It should cross through all of the error bars

It should have an even number of points above and below

12
Q

What is a line of worst fit?

A

The least acceptable straight line through the data points (steepest or shallowest)

13
Q

What is the absolute uncertainty of a gradient and how is it calculated?

A

The positive difference between the gradient of the line of best fit and the gradient of the line of worst fit

14
Q

How is the percentage uncertainty of a gradient calculated?

A

% uncertainty = absolute uncertainty / best fit gradient x 100

15
Q

How is percentage difference calculated?

A

% difference = (calculated value - true value) / true value x 100

16
Q

How is the maximum value calculated?

A

Measured value + absolute uncertainty

17
Q

How is the minimum value calculated?

A

Measured quantity - absolute uncertainty