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Flashcards in prep for the ISA and General physics Deck (24)
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1
Q

When recording results in a table, how many significant figures do you give it to?

A

Give it to the no. of significant levels of the instruments.

Give any means calculated to the same no. of significance levels.

2
Q

If you process data which are given to different numbers of significant figures, how many do you use in the answer?

A

The no. of significant figures used in the value with the smallest amount.

3
Q

How can random errors be reduced?

A

Taking repeat readings.

4
Q

What is systematic error?

A

Errors that show a trend, bias or pattern. It deviates from the true reading by a fixed amount each time.

5
Q

How is the uncertainty in a set of values found?

A

There are 3 options.
Random error. Uncertainty=(±range÷2) units.
Precision of instrument. Uncertainty=± smallest units on the scale.
Judgment. Like having kinks in a wire. Uncertainty=±(3 X precision of the instrument.)
Pick the largest.
Always have units.

6
Q

If we have to combine the errors from different measurements and they have different units, what do we do?

A

Find % uncertainty.
(Uncertainty ÷ mean value.) X 100.
Never give to more than 2 sig figs.

7
Q

How do you combine % uncertainties ?

A

They add up if you X, +, - or ÷
If a value is squared, multiply it by 2.
If a value is square rooted, divide by 2.

8
Q

How would you find the percentage of something?

How would you find 1.3% of 9.42?

A

(9.42÷100) X 1.3

9
Q

What is an accurate measurement?

A

An accurate measurement is one where independent measurements cluster about the true
value of the measured quantity.

10
Q

What is a precise measurement?

A

A precise measurement is one where independent measurements of the same quantity
closely cluster about a single value that may or may not be the correct value.

11
Q

Does systematic errors affect precision or accuracy?

A

Only the accuracy.

12
Q

When drawing a table, what should each column heading have?

A

A quantity and a unit. The units should be give in brackets.

13
Q

How big should the graph be?

A

Big enough so that the plotted points take up at least half the page.

14
Q

When drawing a graph, when should the axis start ?

A

At the origin. Both should start at 0.

15
Q

When drawing a graph, what divisions in the axis aren’t allowed?

A

3, 6, 7, 9 and others like that.

16
Q

Should the line of best fir go through the origin?

A

Only if it fits the data. Don’t force it through.

17
Q

What are the units used for the gradient?

A

There aren’t any.

18
Q

How do you know if a set of results are reliable?

A

The repeat values are similar to each other and they area close to the line of best fit.

19
Q

What are control variables?

A

variables that you couldn’t have changed, like equipment you were given.

20
Q

How can reliability be improved?

A

Take repeat readings.

21
Q

How can valibilty be improved?

A

A larger range and more repeat values.

22
Q

Why might some results not be reliable?

A

not reliable because (some of) the points are not

very close to the line of best fi

23
Q

What will you have to do in the isa?

A

Calculate percentage uncertainties.
Design your own experiment.
Efficiency volatge÷emf
You will have to use power equations.

24
Q

Why is it important to test by experiment the prediction of scientific theory?

A

As if a reliable experiment doesn’t support the hypothesis, the hypothesis must be changed.