Units of Measure

Question 1

SI unit of temperature

Answer 1

Kelvin (K) - Starts at Absolute Zero - 0 Celsius = 273 K - Named after Scottish physicist William Lord Kelvin

Question 2

SI unit of electric current

Answer 2

Ampere (A) - Often shortened to amp - Named after French father of electrodynamics Andre-Marie Ampere - Expresses flow rate of electric charge, with the equation i (amps) = q (charge) / t (time)

Question 3

SI unit for amount of substance

Answer 3

Mole (mol) - Amount of a substance that contains as many entities (atoms, molecules, etc) as atoms in 12 g of pure carbon - Number of molecules in a mole is known as Avogadro’s Constant)

Question 4

SI derived unit of pressure

Answer 4

Pascal (Pa) - One Newton per Sq Meter - Named after French polymath Blaise Pascal - 1 atmosphere = 101 kPa (avg pressure at sea level)

Question 5

SI unit of electric charge

Answer 5

Coulomb (C) - Named for French physicist Charles-Augustin de Coulomb - The charge transported by one amp in one second - A measure of the concentration of electrons (one unit volume of electrons)

Question 6

SI unit of luminous intensity

Answer 6

Candela (cd) - 1 cd is roughly equal to the amount of light given off from one common candle

Question 7

SI derived unit of power

Answer 7

Watt (W) - One joule per second - Named after Scottish engineer James Watt

Question 8

SI derived unit of energy

Answer 8

Joule (J) - Named for English physicist James Joule - Equal to the energy transferred to an object by one Newton of force over one meter

Question 9

SI derived unit of force

Answer 9

Newton (N) - The force needed to accelerate one kg of mass at the rate of 1 meter per second squared

Question 10

SI derived unit of electrical potential

Answer 10

Volt (V) - Named for Italian physicist Alessandro Volta who invented the Voltaic Pile, first chemical battery - Refers to the potential electrical energy an object contains, which could be released - A measure of the difference in concentration of electrons between two places

Question 11

SI derived unit of electrical resistance

Answer 11

Ohm (omega symbol) - Named for German physicist Georg Ohm - A measure of the resistance to electron motion caused by some medium

Question 12

pH of common liquids

Answer 12

pH stands for Power or Potential of Hydrogen

14 - Very basic - Bleach, lye
11 - Ammonia
9 - Baking soda
7 - Neutral - Water, blood
5 - Black coffee
3 - Soda, tomato juice
0 - Very acidic - Battery acid, hydrochloric acid

Question 13

Ångström

Answer 13

A unit of length equal to 10^-10 meters (one ten-billionth of a meter) - Approximately the size of an atom - Denoted by the symbol Å - Used especially to measure the wavelength of electromagnetic radiation or distances between atoms - Named for Swedish physicist Anders Jonas Ångström

Question 14

SI derived unit of radioactivity

Answer 14

Becquerel (Bq) - Defined as the activity of a quantity of radioactive material in which one nucleus decays per second - Succeeded the curie (Ci), an older non-SI unit of radioactivity based on the activity of 1 gram of radium-226 - Named for French physicist Henri Becquerel (1852-1908)

Question 15

SI derived unit of electrical capacitance

Answer 15

Farad (F) - The capacitance which stores a one-coulomb charge across a potential difference of one volt - Measures the ability of a body to store an electrical charge - Most electrical applications use picofarads (one trillionth) or nanofarads (one billionth) - Named after scientist Michael Faraday

Question 16

Micron

Answer 16

Unit of length equal to 10^-6 meters - One millionth of a meter - AKA micrometre, symbol μm

1-10 μm - Length of bacteria
10 μm- Length of human chromosome
20-180 μm - Human hair
70-180 μm - Thickness of paper