In a grease spot photometer light from a lamp with dirty chimney is exactly balanced by a point
Channel: Doubtnut
Date: 2020-08-23

In a grease spot photometer light from a lamp with dirty chimney is exactly balanced by a point source distance 10 cm from the grease spot. On clearing the chimney, the point source is moved 2 cm to obtain balance again. The percentage of light absorbed by dirty chimney is nearly