Question

Anyone willing to discuss absolute, random, and systematic errors in labs?

Answer 1

Sometimes it is useful to be able to put a number to the size of the error –rather than
“about that much”. You may have heard the term “Half smallest scale division” for an
estimate of experimental error. If you were measuring a 23cm wide book with a ruler
with 1cm divisions (think of the large 1m rulers), the absolute error would be ± 0.5cm.
The absolute error is ± half of the smallest division you can measure with the ruler. The
measurement of the width of the book would be written as 23 ± 0.5cm.
If you had a more accurate ruler with divisions of 1mm (a standard ruler you would find)
what would the absolute error be? (in cm)

Answer 2

Not sure I'll be much help on this one....I have a general idea of what those types of errors are though.

Answer 3

ok. Do you think you know how they came up with +/- 0.5 cm? I think if I knew that, I would be able to answer the question.

Answer 4

Yes...because that's half way between the divisions on the ruler. If the ruler was broken into mm as the question states, the absolute error would change from 0.5cm to be 1/2 a mm...or 0.0005 cm

Answer 5

The key here is the term “Half smallest scale division”

Answer 6

it makes a lot more sense now. So, let's say you have division of 0.05mm, the absolute error would be 0.025 mm or 0.0025 cm ?

Answer 7

oops

Answer 8

But you have the idea

Answer 9

great well! thanks heaps :)

Answer 10

my pleasure :)

Answer 11

You were right on the conversion...my mind isn't working right today

Answer 12

no worris ;)