Synoptic

Question 1

critique results model answer

Answer 1

• Comment on precision (sig fig consistency)
• repeat reading
• enough results
• look for inconsistent intervals between readings

Question 2

making results more accurate

Answer 2

• parallax error (record at eye level)
• fiducial markers as reference points
• set square to make sure rulers are vertical
• averages to reduce random error

Question 3

absolute uncertaintity

Answer 3

the uncertainty from the measuring device

Question 4

uncertainty of repeat readings

Answer 4

uncertainty = half the range of the repeats

data = mean +- uncertaintity

Question 5

percentage uncertaintity

Answer 5

absolute uncertainty / reading * 100

Question 6

accurate

Answer 6

near the true value

Question 7

precise

Answer 7

results are grouped together

Question 8

compounding uncertainties

Answer 8

1. convert absolute uncertainty to percentage uncertainty
2. combine the uncertainties
3. convert back to absolute uncertainties (multiple by value)

Question 9

compound uncertainty rules

Answer 9

• multiplying/ dividing ADD THE UNCERTAINTIES

- powers MULTIPLY BY EXPONENT

Question 10

systematic error

Answer 10

fault with equipment e.g. zero error

Question 11

random error

Answer 11

due to human error e.g. human reaction time

Question 12

reading of a micrometer

Answer 12

• 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

Question 13

reading of a vernier caliper

Answer 13

• 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

Question 14

resolution of a vernier caliper

Answer 14

0.05mm

Question 15

resolution of a micrometer

Answer 15

0.01mm

Question 16

resolution

Answer 16

The smallest division on an instrument

Question 17

why take means

Answer 17

reduce the effect of random errors and spot anomalies

Question 18

error

Answer 18

An error is the difference between the (measured) result and the true value

Question 19

uncertainty

Answer 19

An uncertainty is the interval/range in which the (true) value can be considered to lie

Question 20

reasons for uncertainty

Answer 20

• instrument resolution
• the way that the measurement is made (parallax error, reaction times, zero error)
• a measured constant not being constant

Question 21

how to ensure accurate results

Answer 21

• check for zero error
• measure dimensions in multiple places
• measure for multiple objects then divide by the number (reduces uncertainty)

Question 22

how is light emittted?

Answer 22

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

Question 23

Cathode ray oscilloscope construction

Answer 23

electron gun, deflection system and screen

Question 24

Cathode ray oscilloscope uses

Answer 24

• measuring voltage
• measuring frequency
• looking at phase difference

Question 25

show a graph is a 1/x curve

Answer 25

plot y agaisnt 1/x, it should be a straight line through the origin