Question

A source of light emits a continuous stream of light energy which falls on a given area. Luminous intensity is defined as

• A. luminous energy emitted by the source per second
• B. luminous flux emitted by the source per unit solid angle
• C. luminous flux falling per unit area of a given surface
• D. luminous flux coming per unit area of an illuminated surface

Answer 1

The correct option is B luminous flux emitted by the source per unit solid angle

We have luminous intensity,
$L=\frac{\Phi }{\Omega }$
where $\Phi$ is the luminous flux and $\Omega$ is the solid angle.
Hence luminous intensity can be defined as luminous flux emitted by the source per unit solid angle.