Question { Cognizant, 34893 }

what is the frequency of direct current(dc)?

Answer

Frequency is the reciprocal of time period. Time period is
one which gives the information of quantity varying with
respect to time. In DC current the quantity doesn't varies
with time, where as in AC systems it varies from positive
max to negative max. Hence DC current do not have any frequency.

Question { 5327 }

which is best ac or dc

Answer

DC is the best source of power supply. Because we can store
the DC power in batteries, where as AC cannot be stored.
But for human safety purpose and universality AC has became
most economical way of production and consumption. Also in
case of power losses and harmonics DC holds up wrt to AC.
Generation of AC is quit simple wrt to DC, because
commutator and brushes are required in case of DC
production. AC is consumed as it is produced, ie; use it or
loose it. DC is exemption for this. there are many way by
which DC can be produced with out emitting CO2 to
environment, such as chemically, solar, etc. eventhough
there are some ways to produce AC ecofriendly, but there is
dispute of economy.