Synoptic Flashcards
critique results model answer
- Comment on precision (sig fig consistency)
- repeat reading
- enough results
- look for inconsistent intervals between readings
making results more accurate
- parallax error (record at eye level)
- fiducial markers as reference points
- set square to make sure rulers are vertical
- averages to reduce random error
absolute uncertaintity
the uncertainty from the measuring device
uncertainty of repeat readings
uncertainty = half the range of the repeats
data = mean +- uncertaintity
percentage uncertaintity
absolute uncertainty / reading * 100
accurate
near the true value
precise
results are grouped together
compounding uncertainties
- convert absolute uncertainty to percentage uncertainty
- combine the uncertainties
- convert back to absolute uncertainties (multiple by value)
compound uncertainty rules
- multiplying/ dividing ADD THE UNCERTAINTIES
- powers MULTIPLY BY EXPONENT
systematic error
fault with equipment e.g. zero error
random error
due to human error e.g. human reaction time
reading of a micrometer
- read the first two digits off the barrel (e.g. line above and below is 0.5mm)
- read the value that lines up with the horizontal line on the thimble add this to the previous value
reading of a vernier caliper
- read off the first two numbers e.g. 0.8 by looking at where the second scale begins
- third number is how many notches along until the two lines completely line up
resolution of a vernier caliper
0.05mm
resolution of a micrometer
0.01mm
resolution
The smallest division on an instrument
why take means
reduce the effect of random errors and spot anomalies
error
An error is the difference between the (measured) result and the true value
uncertainty
An uncertainty is the interval/range in which the (true) value can be considered to lie
reasons for uncertainty
- instrument resolution
- the way that the measurement is made (parallax error, reaction times, zero error)
- a measured constant not being constant
how to ensure accurate results
- check for zero error
- measure dimensions in multiple places
- measure for multiple objects then divide by the number (reduces uncertainty)
how is light emittted?
There are electron transitions between energy levels in the atoms when electrons return to a lower level they emit energy in the form of photons
Cathode ray oscilloscope construction
electron gun, deflection system and screen
Cathode ray oscilloscope uses
- measuring voltage
- measuring frequency
- looking at phase difference
show a graph is a 1/x curve
plot y agaisnt 1/x, it should be a straight line through the origin
