measurements and their errors

Question 1

how to reduce random error

Answer 1

repeat measurements several times and calculate an average from them

Question 2

how to reduce systematic error

Answer 2

Instruments should be recalibrated, or different instruments should be used
Corrections or adjustments should be made to the technique

Question 3

what is precision

Answer 3

there is very little spread about the mean value, in other words, how close the measured values are to each other

Question 4

how to calculate percentage uncertainty

Answer 4

%uncertainty = (uncertainty/measured value) x 100%

Question 5

how to find uncertainty in different situations

Answer 5

The uncertainty in a reading: ± half the smallest division
The uncertainty in a measurement: at least ±1 smallest division
The uncertainty in repeated data: half the range i.e. ± ½ (largest - smallest value)
The uncertainty in digital readings: ± the last significant digit unless otherwise quoted

Question 6

combining uncertainties adding/subtracting data

Answer 6

Add together the absolute uncertainties

Question 7

combining uncertainties
multiplying/dividing data

Answer 7

Add the percentage or fractional uncertainties

Question 8

combining uncertainties
raising to a power

Answer 8

Multiply the percentage uncertainty by the power

Question 9

percentage uncertainty in gradient

Answer 9

Question 10

percentage uncertainty in y intercept

Answer 10