33) what is a ccd, and how does it work? why has it replaced photographic plates?

Charge Coupled Device (CCD) : Its work and Reason for replacing photographic plates:

CCD is an electronic system constructed from a semiconductor while the number of photons are recorded with the help of pixels or adjacent small light sensitive sensors, which fall upon it and result by capturing a high degree of resolution picture such device are called as Charge coupled device or CCD.

The replacement of CCD from photographic plate took place as they are much more delicate to light than such a plate and find out about 80 per cent of the photons which falls upon them is compared with less than 2 per cent for the appropriate photographic emulsions.

multiply 2kg by latent heat of vap