Introduction Flashcards
A circuit diagram consisting of lines and symbols is a called…?
schematic diagram
meagre
very small in amount or
Lord Kelvin said “When you can measure what you speak about, and express it in numbers, you know something about it; but when you cannot measure it, when you cannot ________ it in numbers, your knowledge is of a meagre and unsatisfactory kind.”
Lord Kelvin said “When you can measure what you speak about, and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind.”
Where did the metric system come from and when?
in France ~1800
What led to the International Bureau of Weights and Measures (BIPM) to provide measurements standards for global use?
after a treaty signed in 1875 by 17 nations’ representatives.
When did the Institute of Electrical and Electronics Engineers (IEEE) adopt the International System of Units (SI)?
October 1965
Where did the Institute of Electrical and Electronics Engineers (IEEE) adopt the International System of Units (SI)?
at the 11th General Conference on Weights and Measures (CGPM) in France in 1960
The base unit of length or distance in the International System of Units is…?
…the metre
What was the metre originally calculated as?
ten-millionth (1 × 10⁻⁷)
From where on Earth was the metre calculated as?
at sea level from the Earth’s equator to the pole
How much is a metre now defined as the distance travelled by light through vacuum?
A meter is now defined as the speed of light in vacuum in 1/299 792 458 sec.
What does the metric system use to separate a group of three numbers and what does the imperial system use?
The metric system uses spaces and the imperial system uses commas.
E.g. Metric system: 299 792 458
Imperial system: 299, 792, 458
What was gram, the original mass metric unit, defined as?
a cubic centimeter of pure water’s mass at 4°C
What’s the SI base unit for mass now?
1000 grams (the kilogram)
What was the original reference of the international standard for the kilogram, a century ago?
the International Prototype of the Kilogram (IPK), a platinum-iridium cylinder at constant temperature and humidity
Where was the reference of the international standard for the kilogram kept?
in Sèvres, France.
Which unit was the last to be based on a physical object?
the kilogram
Why and when was the definition of a kilogram official changed?
on May 2019 to improve precision and remove dependence on a physical object
What was a second originally defined as?
1/86 400 of a mean solar day
What do we now define a second as?
in terms of the decay of radioactive cesium in an atomic clock
What’s the SI unit for temperature?
kelvin (K)
How much Celsius degree is a kelvin equal to?
1 kelvin = 1 celsius degree
What’s the freezing and boiling point of water on the Celsius scale
freezing point: 0°C
boiling point: 100°C
