Question

define seven basi SI units

Answer 1

Dear Student,

• Metre : The metre is the length of the path travelled by light in vacuum during a time interval of 1/299,792,458 second.
• Kilogram : The kilogram is the unit of mass equal to the mass of the international prototype of kilogram.
• Second : The second is the duration of 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levers (F = 4, mF = 0 to F = 3, mF = 0) of the ground state of the cesium 133 atom.
• Ampere : The ampere is the constant current which, if maintained in two straight parallel conductors of infinite length, of negligible circular cross-section, and placed 1 metre apart in vacuum, would produce between these conductors a force equal to 2 x10^-7 Newton per meter of length
• Kelvin : The Kelvin, unit of thermodynamic temperature is the fraction 1/273.16 of the thermodynamic temperature of the triple point of water.
• Mole : The mole is the mount of substance of a system which contains as many elementary entities as there are atoms in 0.012 kg of carbon 12 (about 6.022 x 10²³ atoms). When the mole is used, the elementary entities must be specified and may be atoms, molecules, ions, electrons, other particles, or specified groups of such particles.
• Candela : The candela is the luminous intensity, in a given direction, of a source that emits monochromatic radiation of frequency 540 x 10¹² Hz and that has a radiant intensity in that direction of 1/683 watt per steradian.

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