Paper 3 practical questions

Question 1

Why does it matter if the measuring instrument is analouge or digital?

Answer 1

• If it is analogue the uncerntainty is half the smallest scale division
• If it is digital it is just the smallest scale division

Question 2

What is F.S.D

Answer 2

Full scale defelction (maximum value it can measure)

Question 3

How many measuremnts are needed for a straight line graph?

Answer 3

7 measurements per straight line across the widest range

Question 4

How should you take measurements for a graph that curves

Answer 4

Take more mesasurements around a turning point

Question 5

What should you check before using an electrical piece of equipment.

Answer 5

Check for non-zero errors

Question 6

If a piece of equipment has a constant non-zero error what sort of error is this?

Answer 6

systematic error

Question 7

If a piece of equipment has a vairable non-zero error what sort of error is this and how to fix this?

Answer 7

• random error
• Take repeated measurements or take long time measurements (gets rid of start and stop errors)

Question 8

how many dp should you record results to?

Answer 8

write down all the decimal points the device provides

Question 9

What is the uncertainty in repeated measuerments?

Answer 9

half of the range

Question 10

Why plot a graph of data?

Answer 10

• Smooth or average the effects of random error on my data to fit a line or curve
• Identify systematic errors through the y-int or x-int
• obtain the gradient from the best fit line
• find the worst best fit by using error bars and compare to the best fit line and obtain an uncertainty
• compare the data to a known equation and plot a graph that gives a straight line
• extrapolate data