Seems like my understanding of difference between Voltage and current is wrong.. Thank you wiebel. I guess i understand what you mean . This helped. And thanks to everyone too..

Sorry for language problem.. But if it is limiting the 2/3 of water what it has to do with the amount of water the tribune need to run efficiently ( 2 volts in the problem) ?.. I mean if we want to calculate something related with tribune it sound logical to use the amount of water tribune received.. Not the amount of water limited... Maybe i am missing something ..?

MITU.. If I increase r2 so how can I provide 0.7 volt 2N2222 transistor requires.?

So another 2N2222 will do the job ?