To truly understand the reason for the gaping difference between the exchange rates of the US$ and The INR you'll have to do some extensive research on the following topics:-
BOP position of a nation: If the balance of payment (BOP) position of a country is favorable. i.e more surplus than deficit It generally has a positive effect on the exchange rate of a country.
Balance Of Payments (BOP) Definition
Interest rate of a nation: If the interest rate of a nation is considerably high it should generally have a positive effect on the Country's exchange rate.