Practical skills - paper 1 and 2 Flashcards

To revise key practical terms (Paper 1 and 2)

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1
Q

Define an independant variable

A

The one variable that you change

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2
Q

Define a dependant variable

A

The variable that you measure

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3
Q

Define a control variable

A

Any variable you keep the same to make it a fair test

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4
Q

Define directly proportional

A

If one variable increases the other variable increases at the same rate. eg if x doubles then y must double.

A graph would be a straight line** through the **origin

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5
Q

Define inversely proportional

A

If one variable increases the other variable decreases at the same rate. eg if x doubles then y must halve

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6
Q

Define an anomalous result

A

An result which does fit the pattern of trend

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7
Q

What should you do if you have an anomolus result?

A

Repeat the reading

Ignore it when calculating the average

Circle on the graph and not include it in your line of best fit

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8
Q

Define interval

A

The spacing between measurements eg 0, 10, 20, 30 40, 50 cm would have an interval of 10 cm

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9
Q

Define range

A

The maximum and minimum values eg 0, 10, 20, 30, 40, 50 cm would have a range of 50 to 0 cm

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10
Q

Define resolution

A

The smallest change that can be measured with a particular piece of equipment

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11
Q

If a stop clock reads 18.72 seconds, what is its resolution?

A

0.01 s

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12
Q

If a voltmeter reads 3.6 V what is its resolution?

A

0.1 V

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13
Q

How can the uncertainty in a measurement be measured?

A

Half of the range

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14
Q

When should you draw a line graph

A

When both variables are continuous

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15
Q

When should you draw a bar graph

A

If one of the variables is discrete or categoric

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16
Q

Define a continuos variable

A

Can be recored as any number eg time, mass, volume

17
Q

Define a discrete variable

A

Can be recored only as a whole number eg number of goals in a match, leaves on a plant

18
Q

Define a catergoic variable

A

Is recorded in words instead of numbers eg colours or types of metal

19
Q

Vernier calipers can measure distance to the nearest 0.01 cm. A meter ruler can measure to the nearest 0.1 cm. Which would be better for measuring the width of an object?

A

The Vernier calipers have a higher** resolution. The meter ruler has a **lower resolution. The Vernier calipers would be more accurate.

20
Q

How can you convert from cm3 into m3?

A

Divide by 1000000 (1003)

21
Q

How can you convert from mm3 into m3?

A

Divide by 1000000000 (10003)

22
Q

Define a random error and give an example

A

A random error is an error in a measurement that is different each time. This causes points to be scattered around a line of best fit on a graph.

An example would be using a stopwatch and starting or stopping it too early

23
Q

Define a systematic (zero) error and give an example

A

An error that will be the same on all measurements. For example an electronic balance that reads 0.05 g before anything is place on it. All readings will be 0.05 g too high.

24
Q

If an electronic balance has a zero error (records a reading when it should say 0.00 ) how could this be corrected?

A
  1. Reset the balance to zero
  2. Record the zero error and add or subtract it from all your measurements
25
Q

What are the benefits of peer review?

A

detects false claims

detects inaccurate data

detects bias

verifies new data

26
Q

How can you check if results are precise?

A

Take repeat readings. If the results are close together then they are precise.

27
Q

What are the benefits of repeat readings?

A

Spot anomalies

Calculate an average

The average should reduce the effect of random errors.

28
Q

What is the difference between accurate readings and precise readings?

A

Accurate readings - average will be close to the true value

Precise readings - repeat readings will be close to each other