Question

Which of the following is the unit of luminous intensity?
A. Mole
B. Candela
C. Kelvin
D. Ampere

Answer 1

Hint – One should remember all the seven base fundamental units which have been given by the International System of Units and from these 7 base units, units of all other quantities can be found. The 7 physical fundamental units are mole, kelvin, ampere, meter, kilogram, second, and candela used for amount of substance, temperature, electric current, length, mass, time and luminous intensity respectively.

Complete step-by-step answer:
Luminous intensity is a one of the 7 fundamental physical quantities which is measured in base fundamental unit or physical fundamental unit.
The SI unit of luminous intensity is a candela.
Mole, which is one of 7 base units, is the SI unit of amount of substance.
Kelvin, which is also one of 7 base units, is the SI unit of temperature.
Ampere is one of 7 base units of the SI unit of electric current.
Therefore, the luminous unit is candela and so option (B) is the correct answer.

Additional information –
Luminous intensity is defined in photometry as the measure of the power, wavelength weighted which is released by a light source in a specific direction based on the luminosity. It is a standard model which represents its sensitivity in the visible light by the human eye. Other units of luminous intensity are – Hefnerkerze and candle power.

Note – Luminous intensity should not be confused with luminous flux, which is another photometric unit, and it is power perceived (in candela) per unit of solid angle (in steradians). Therefore, lumen is the SI unit of luminous flux.