how can i control force with colour look at my file and plzz help me out.

You need to work more organized because you all your little mistakes make effect on your result. and when you change a parameter and that doesn't help you for fixing your problem just turn it back to its default.
I did these:
a close } at the end of vex code
insert your sop path in popobject.
I disabled popsource1 and popgrains1
changed your force activation back to 1

thankx for the reply..
but doing so the particles r not behaving like grains particles and when i enable popgrains1 nd popsource1 all black and white particles r comming down but very unproperly any suggesion how to correct that..