What is the relationship between intensity and amplitude?

[Raghav Gupta]

I think basic definition of intensity is power by area.
How intensity is square of the amplitude?
How intensity is energy density times speed of thing?
How in a radiation of EM wave,
Half of the intensity is provided by elec.field and other by magnetic field?

 

[AdityaDev]

NCERT example 8.5 right?

 

[Raghav Gupta]

NCERT example 8.5 right?

Yeah, I got all the answers of that by some searching.
Can you answer this one,
In wave optics
taking size of light source =s and distance from 2 slits S,
How s/S <= λ/d
for the fringe formation to take place?

 

[AdityaDev]

Size of light source??

 

[Raghav Gupta]

Size of light source??

As in NCERT example 10.4 (d) .