measurements and errors

Question 1

What is the SI base unit for luminous intensity?

Answer 1

Candela (cd)

Question 2

What is the SI base unit for temperature?

Answer 2

Kelvin (K)

Question 3

What is the SI base unit for pressure?

Answer 3

Pascales (Pa)

Question 4

What formula is used to convert from Kelvin to Celcius?

Answer 4

C = K - 273

Question 5

What multiplier is nano?

Answer 5

10^−9

Question 6

What multiplier is micro?

Answer 6

10^-6

Question 7

What multiplier is milli?

Answer 7

10^-3

Question 8

What multiplier is centi?

Answer 8

10^-2

Question 9

What multiplier is mega?

Answer 9

10^6

Question 10

What multiplier is giga?

Answer 10

10^9

Question 11

Which of these is equal to 0.003 seconds?
>3ns 
>3ks
>3ms
>3s

Answer 11

> 3ms

Question 12

How many inches are in a foot?

Answer 12

12 inches = 1 foot

Question 13

What is the uncertainty about measurements called?

Answer 13

Error

Observed value = true value + error

Question 14

The error in our measurements is made up of what 2 parts?

Answer 14

Random

systematic

Question 15

TRUE OR FALSE: Systematic errors cannot be reduced by repeats

Answer 15

True

Question 16

What is a systematic error?

Answer 16

Error that follows a set pattern but a random error doesn’t

Question 17

How can you reduce a systematic error?

Answer 17

Use the measuring equipment to measure a known value. This process is known as calibration

Question 18

name an example of a systematic error

Answer 18

Zero error (or calibration error

Question 19

Explain the difference between accuracy and precision

Answer 19

Accuracy - How close it is to the true value

Precision - How close each repeated measurements are

Question 20

Explain the difference between reproducibility and repeatability

Answer 20

Reproducibility - Different person gets the same result

Repeatability - Same person gets same results (within random errors)

Question 21

What is the resolution of a measuring equipment?

Answer 21

Describes its maximum precision

Question 22

Define “absolute uncertainty”

Answer 22

Range of possible real values

Question 23

Define “fractional uncertainty” and how do you calculate it?

Answer 23

Absolute uncertainty/measured value

Question 24

Define “percentage uncertainty” and how do you calculate it?

Answer 24

Fractional uncertainty as a percentage

Question 25

What do we call the line on an uncertainty graph?

Answer 25

Error bar

Question 26

How can we spot a systematic uncertainty from a graph?

Answer 26

By spotting if the theory and the results do not match when the independent variable is zero
Etc when measuring the current in a circuit we would expect to the current to be zero when the supply potential difference is zero

Question 27

If there is a systematic uncertainty what would the intercept be?

Answer 27

Not zero
Intercept indicates size of systematic error and once it has been found we can use the graph to find an estimate for the random error

Question 28

What can error bars show?

Answer 28

Steepest(g1)/shallowest(g2) line of best fit

Question 29

Graph uncertainty equation?

Answer 29

The uncertainty is equal to the average of the steepest gradient and the shallowest gradient, take away half of the steepest gradient minus the shallowest gradient.

Question 30

Define “order of magnitude”

Answer 30

A power of 10 that most closely approximates it - refers to the scale of a value