Physics · Dawn of Modern Physics

The candela is the luminous intensity, in the perpendicular direction, of a surface of 1/600000 square meters of a blackbody at the temperature of freezing platinum under a pressure of 101325 newtons per square meter.

The candela is the luminous intensity, in the perpendicular direction, of a surface of 1/600000 square meters of a blackbody at the temperature of freezing platinum under a pressure of 101325 newtons per square meter.

The candela (symbol: cd) is the SI base unit of luminous intensity; that is, power emitted by a light source in a particular direction, weighted by the luminosity function. A common candle emits light with a luminous intensity of roughly 1 cd.

The definition is this SI unit is given as

 "The candela is the luminous intensity, in the perpendicular direction, of a surface of 1/600000 square meter of a blackbody at the temperature of freezing platinum under a pressure of 101325 newtons per square meter."

Hence all options other than B are incorrect.

The candela is the luminous intensity, in the perpendicular direction, of a surface of 1/600000 square meters of a blackbody at the temperature of freezing platinum under a pressure of 101325 newtons per square meter.

The candela is the luminous intensity, in the perpendicular direction, of a surface of 1/600000 square meters of a blackbody at the temperature of freezing platinum under a pressure of 101325 newtons per square meter.

The candela is the luminous intensity, in the perpendicular direction, of a surface of 1/600000 square meters of a blackbody at the temperature of freezing platinum under a pressure of 101325 newtons per square meter.