[TrevorJ]

I don't know about India but in the states you can get model rockets or those pop-bottle water rocket kits. Maybe some creative rigging with a postage scale to measure forces and demonstrate the equal/opposite reaction of throwing matter (water) out the back of the rocket at high speed?

Electromagnetic stuff: here's instructions on making a motor out of some wire, a magnet and a double-A battery. http://www.ehow.com/how_4422383_make-battery-motor.html

Other thoughts would be to check out instructibles.com, it's not geared towards science but a lot of the projects outlined could easily be used to demonstrate principles.