2 No. 2: Measurement of luminous intensity by using photometric bench

1. INTRODUCTION

Luminous intensity in a given direction of the point source of light or the very small area
of source of light is called the proportion between the elementary luminous flux that fits into the infinitesimal cone connected with the given direction and the sold angle
of this cone. The proper formula is presented by (1). The “candela” is the unit of luminous intensity and one of the base unit of the International System of Units – SI. The candela
is the luminous intensity, in a given direction, of a source that emits monochromatic radiation of frequency 540×1012 hertz and that has a radiant intensity in that direction
of [latex]1 \over 683[/latex] watt per steradian.