Since the two options are identical in the given question, one is led to believe there is punctuation missing.
However, there are several possible uses and both are used. DC is direct current, used in electronics and electricity; D.C. is the District of Colombia and the seat of government in the USA.
converting dc current to dc in different voltage rating
12v dc to 3v dc
dc is a comic brand or dc is Washinton, D.C.
Dc stands for the district of Columbia (dc)
Dc chopper is a static device which converts constant dc source to variable dc.
DC refers to the District of Columbia, which is not a state.
chopper is a circuitry to convert DC-DC for eg: 116v dc to 150v dc.
DC can stand for "direct current" which is what you get from a battery. dc-in would be a connection for DC input.
With an appropriately rated DC to DC converter.
E dc dc e dc dc eee cf eee fd edc dc thants the chorus
luo converter is a new technique adopted for dc to dc voltage lifting(dc voltage boosting)...
A dc series motor can work on dc and ac because dc motors are totally reversible.