engineering recuitment PGCIL Diploma Trainee Mock Test 2024 Utilization of Electrical Energy Illumination
Luminous efficiency = ?
1
\(\rm \frac {Brightness}{Power \,input}\)
2
\(\rm \frac {Luminous \,flux}{Power \,input}\)
3
\(\rm \frac {Luminous\,flux}{Power \,output}\)
4
\(\rm \frac {Power \,input}{Power \,output}\)