how can you equate centripetal force with electrostatic force in the case of an electron revolving around the nucleus.both are acting towards the centre . how can they balance each other

According to bohr's eletrostatic force of attraction....the F(e) between the revolving elelctons and nucleus provides the necessary centripetal force F(c)...so one force provides another and can be equated....

Dear student,

in case of electron revolving around the nucleus centrifugal force is balenced by electrostatic force.

and centrifugal force and electrostatic force are in opposite direction ..

or mathematically ,   ke²/r²=mv²/r

Thanks and Reward

Adarsh