Test: Introduction to SI Units List - UPSC MCQ

The base unit of time in the International System of Units (SI) is the second. It is defined as the duration of 9,192,631,770 periods of the radiation corresponding to the transition between two hyperfine levels of the ground state of the cesium-133 atom.

The SI unit of electric current is the ampere. It is defined as the constant current that, if maintained in two straight parallel conductors of infinite length, of negligible circular cross-section, and placed one meter apart in a vacuum, would produce between these conductors a force equal to 2 x 10⁻⁷ newtons per meter of length.

The SI unit of temperature is the kelvin. It is defined as 1/273.16 of the thermodynamic temperature of the triple point of water. The kelvin scale is an absolute temperature scale with 0 K representing absolute zero, the point at which all molecular motion ceases.

The SI unit of luminous intensity is the candela. It is defined as the luminous intensity in a given direction of a source that emits monochromatic radiation of frequency 540 x 10¹² hertz and that has a radiant intensity in that direction of 1/683 watt per steradian.

The SI unit of amount of substance is the mole. It is defined as the amount of substance that contains as many elementary entities (atoms, molecules, ions, etc.) as there are atoms in exactly 0.012 kilograms of carbon-12.

The SI unit of length is the meter. It is defined as the distance traveled by light in a vacuum during a time interval of 1/299,792,458 of a second. The meter is currently defined in terms of the speed of light.

The SI unit of mass is the kilogram. It is defined as the mass of the international prototype of the kilogram, a platinum-iridium cylinder kept at the International Bureau of Weights and Measures in France. However, it's worth noting that the kilogram is expected to be redefined in terms of fundamental constants in the near future.

The SI unit of electric potential or electromotive force is the volt. It is defined as the potential difference across a conductor when a current of 1 ampere dissipates 1 watt of power.

The SI unit of luminous flux is the lumen (lm). One lumen is defined as the luminous flux of light produced by a light source that emits 1 cd of luminous intensity over a solid angle of 1 sr. In other systems of units, luminous flux may have units of power.

The SI unit of force is the newton. It is defined as the force required to accelerate a mass of one kilogram at a rate of one meter per second squared.

The SI unit of frequency is the hertz. It is defined as one cycle per second. It is commonly used to measure the frequency of periodic phenomena such as vibrations, oscillations, and electromagnetic waves.

The SI unit of energy is the joule. It is defined as the work done when a force of one newton acts over a distance of one meter.

The SI unit of power is the watt. It is defined as one joule of energy transferred per second. It is commonly used to measure the rate of energy transfer or conversion.

The SI unit of pressure is the pascal. It is defined as one newton of force applied per square meter of area.

The SI unit of electric resistance is the ohm. It is defined as the resistance between two points of a conductor when a constant potential difference of one volt, applied to these points, produces a current of one ampere.

The SI unit of electric charge is the coulomb. It is defined as the amount of electric charge carried by a current of one ampere in one second.

The SI unit of capacitance is the farad. It is defined as one coulomb of electric charge stored per volt of potential difference across a capacitor.

The SI unit of magnetic flux is the weber. It is defined as the magnetic flux that, linking a circuit of one turn, produces an electromotive force of one volt when the flux is uniformly reduced to zero within one second.

The SI unit of magnetic field strength is the ampere per meter. It is defined as the magnetic field produced by a current of one ampere flowing through a conductor per meter of distance around the conductor.

The SI unit of electric conductance is the siemens. It is defined as the reciprocal of the ohm and is equal to one ampere per volt.