Measurements And Their Errors
SI Units And Prefixes
● SI Units (International System of Units) are fundamental base units
● Idea is they cannot be simplified (‘broken down’) into any smaller units
Prefixes
● Tera (T) - 1012
● Giga (G) - 109
● Mega (M) - 106
● Kila (k) - 103
● Centi (c) - 102
● Milli (m) - 10-3
● Micro (µ) - 10-6
● Nano (n) - 10-9
● Pico (p) - 10-12
● Femto (f) - 10-15
Limitation of Physical Measurements
Random Errors
● Occur when measurements are being made
● Result in measurements varying in unpredictable ways
● Can’t control the factors causing variation so can’t correct error
● Fixed by taking many measurements and finding mean
● Example:
○ Resistor rated at 12Ω measures as 12.5, 12 or even 14 with a
multimeter
○ Variation could be due to change in temp., due to current or difficulty
using multimeter
○ Rated resistance is the average resistance
Systematic Errors
● Occur when measurements being made
● Result in measurements varying in consistent ways
SI Units And Prefixes
● SI Units (International System of Units) are fundamental base units
● Idea is they cannot be simplified (‘broken down’) into any smaller units
Prefixes
● Tera (T) - 1012
● Giga (G) - 109
● Mega (M) - 106
● Kila (k) - 103
● Centi (c) - 102
● Milli (m) - 10-3
● Micro (µ) - 10-6
● Nano (n) - 10-9
● Pico (p) - 10-12
● Femto (f) - 10-15
Limitation of Physical Measurements
Random Errors
● Occur when measurements are being made
● Result in measurements varying in unpredictable ways
● Can’t control the factors causing variation so can’t correct error
● Fixed by taking many measurements and finding mean
● Example:
○ Resistor rated at 12Ω measures as 12.5, 12 or even 14 with a
multimeter
○ Variation could be due to change in temp., due to current or difficulty
using multimeter
○ Rated resistance is the average resistance
Systematic Errors
● Occur when measurements being made
● Result in measurements varying in consistent ways
