Measurements and uncertainties

Question 1

permittivity of free space

Answer 1

8.854 x 10^-12

Question 2

Prefixes
T,G,M,k,m,μ,n,p

Answer 2

T - 10^12
G - 10^9
M - 10^6
k - 10^3
m - 10^-3
μ - 10^-6
n - 10^-9
p - 10^-12

Question 3

• 1eV
• charge of electron
• 1kWh

Answer 3

• 1eV = 1.60 x 10^-19 J
• charge of electron = -1.60 x 10^-19 C
• 1kWh = 3.6 x 10^6 J

Question 4

accuracy
precision
repeatable
resolution

Answer 4

accuracy - how close to the true value
precision - how close together readings are
repeatable - get same results every time
resolution - smallest unit of measurement on the instrument

Question 5

Celsius to Kelvin

Answer 5

C + 273 = K

Question 6

two types of uncertainty and how to get them

Answer 6

absolute uncertainty
SINGLE ±smallest unit of measurement
REPEAT ± range if series of measurements

percentage uncertainty
SINGLE absolute uncertainty/measured value x 100
REPEAT half the range/mean measured value x 100

Question 7

reading vs measurement and uncertainties for each

Answer 7

reading - 1 judgment
± half smallest division

measurement - 2 judgements
± smallest scale division

Question 8

error bar length on graph

Answer 8

range of data
- half range
+ half range

Question 9

uncertainty for x if
x = y + z
x = y - z

Answer 9

x absolute uncertainty = y absolute uncertainty + z absolute uncertainty

Question 10

uncertainty for x if
x = yz
x = y/z

Answer 10

x percentage uncertainty = y percentage uncertainty + z percentage uncertainty

Question 11

x = y^A

Answer 11

x percentage uncertainty = y percentage uncertainty x A