I am writing about currents like AC and DC types. AC stands for Alternating Current and DC stands for Direct Current. Would it make sense when writing if i wrote like this: "I am going to use DC current" or "I am going to use DC"? It sounds grammatically wrong when saying "DC current", because i am repeating current twice in an expanded form of DC. But when saying just "DC", it also sounds wrong, because I'm not describing what DC is.

Can you please tell me which is the correct form? Thanks for your time.

  • 4
    If you will use DC or AC repeatedly, you could spell it out the first time so less awkward in abbreviated form later as a noun instead of adjective. E.g., "I will be using direct current (DC)." (although a sentence more specific to your topic might suit, e.g. "DC sources" or "direct-current batteries"). "AC current" is redundant (in a syntactically incorrect way) as is "ATM machine" and "PIN number".
    – 11qq00
    Commented Sep 7, 2021 at 3:58
  • Yes, good point.
    – cool bean
    Commented Sep 7, 2021 at 4:14
  • 1
    Correct usage and satisfaction of one's logical arguments for a usage are not always the same thing. Definitions usually broaden, and sometimes even switch, over time. Commented Sep 7, 2021 at 11:57
  • 1
    There are a lot of similar questions about phrases such as PIN number, e.g. english.stackexchange.com/questions/14868/…
    – Stuart F
    Commented Sep 7, 2021 at 12:33
  • When a techie uses the term "DC" he/she hardly recalls that the "C" stands for "current".
    – Hot Licks
    Commented Sep 7, 2021 at 13:18

2 Answers 2


As you have pointed out already, saying "DC/AC current" would mean you're repeating current twice. One wouldn't say "DC current is the one-directional flow" but rather, "DC is the one-directional flow".

A (probable) reason why the second sentence sounds weird is because is because, technically, you wouldn't say you're using DC but instead you're using a DC source.

"I am going to use a direct current (DC) source."


Did some extra research, because Physics isn't really my area of expertise. According to Wikipedia:

The abbreviations AC and DC are often used to mean simply alternating and direct, as when they modify current or voltage.

This means that it is, in fact, socially acceptable to say "DC current" & "AC current" despite its redundancy.

  • 1
    Thank you for clarifying my first doubt :) .But what if the context was: "In the wire, there is DC source". 'source', doesn't make sense here, so would 'current' here be an exemption?
    – cool bean
    Commented Sep 7, 2021 at 4:13
  • 1
    For those instances, you could always expand DC: "direct current flows through wire A". (PS: I've updated my answer a bit) Commented Sep 7, 2021 at 4:30
  • 1
    Thanks for taking your time to answer my question.
    – cool bean
    Commented Sep 7, 2021 at 5:53
  • I'm surprised that justification for 'DC current' is out there. Good trawling! But please add a link to the Wikipedia reference. // 'PIN Number' is another common redundancy. Commented Sep 7, 2021 at 11:39

DC current is in common use:

The abbreviation "dc" is so much used that it is common language to say dc current (tautology) and dc voltage (contradictory)... The dc current may be pulsed, but...
A galvanic current is the same as a dc current, and the term is used... S. Grimnes and Ø. G. Martinsen; Bioimpedance and Bioelectrical Basics

What is DC Current?
DC stands for Direct Current, although it is often referred to as “DC Current”. electrical4U.com

To test the setting of the pulse time, two samples are measured in liquid nitrogen with pulse and DC current, and the result ...

Fig. 6.6: Comparison of critical current in liquid nitrogen with DC current supply and pulse current supply. Liu and Yingzhen; Design of a Superconducting DC Wind Generator

The peak current rating of the switches is equal to the DC current source and is lower compared to the VSI case. J. C. Whitaker; The Electronics Handbook

Google Scholar turns up about 3,900 papers with "DC current", for example:

M. Dyakonov and M. Shur; "Shallow water analogy for a ballistic field effect transistor: New mechanism of plasma wave generation by dc current"

N. Deng et al.; "A DC current flow controller for meshed modular multilevel converter multiterminal HVDC grids"

  • @BublooMohanrajh DC current source/supply is fine; see examples.
    – DjinTonic
    Commented Sep 7, 2021 at 12:49

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.