What should be the duration (term ) of my insurance policy?

Ideally, the term of your policy should be equal to the number of years your family will be dependent on you financially. However, ensure that your insurance payment period is also equal to the number of years you plan to work (and hence is not a burden for you).
If you are one of those gentlemen who have been lucky to have a wife that has always been a homemaker, please ensure that you have a pension policy or a whole life policy that takes care of your wife's needs, in your absence as well.

Source: SBI Life Insurance