SI units

Question 1

second

Answer 1

measures time, duration of given number of oscillations of the caesium-133 atom

Question 2

metre

Answer 2

measures distance, length of the path travelled by light in vacuum during a certain fraction of a second

Question 3

mole

Answer 3

measures amount, amount of substance which contains as many elementary particles as there are atoms in 0.012kg of carbon-12

Question 4

ampere

Answer 4

measures current, the current in 2 parellel conductors of infinite length placed 1 metre apart in a vaccume, which would produce between them a force of 2 x 10 mins 7 N/m

Question 5

candela

Answer 5

measures luminous intensity, the luminous intensity in a given direction of a source that emits monochromatic light at a specfic frequency

Question 6

kilogram

Answer 6

mass, the mass of the international prototype of the kilogram held in france

Question 7

kelvin

Answer 7

measures temperature, 1/273.16 of the thermodynamic temperature of the triple point of water