see here the question is abt y radio waves are used in communication even though there r waves wid higher frequency.the only other reason is their wavelenght.

im not sure abt the 2nd question u r asking.

Shorter wavelength radio waves  don't curve around the Earth or reflect from the ionosphere as they travel. they can easily penetrate thru ionosphere and this makes them very useful for long-distance communications. 

so in this, frquency b4 and after remains same???

yes!!!

how did u get it. plz xplain fully.

heres a question on probability!!

in a school there are 1000 students out of which 430 are girls. it is known that out of 430, 10% of girls study in class XII. wat is the probability that a student chosen randomly studies in class XII given that the chosen student is a girl??

 

plz, give an explained solution to this. i didnt get the question.

that i knew!!!

something else???

give a few points of distiction bw astronomical telescope at normal adjustment and when final image is formed at LD frm the eye.