I am working in the field of electrical engineering where losses may appear due to for example and in short, pulsating magnetic fields in magnetic materials (Core losses) or electric current (Copper losses).

Though, after reading many scientific papers written by international scientists, I am still unable to decide whether to use the term "loss" or "losses" to name them.

For example, if you look at the Wikipedia article on Copper losses linked above, you can find both usage :

"Copper losses result from Joule heating..." "Therefore, the energy lost due to copper loss is..."

My question is : when do we use "loss" and when do we use "losses" for this kind of inquiry ?

  • 1
    The noun 'loss' is used both as a mass noun and as a count noun. The count noun is used for 'instances of' or 'totals lost' (United's recent losses have been ... / Lib-Dem losses are ... / Shipping losses were at first ...). The plural is unusual with medical conditions (memory / hearing / hair loss). With 'copper loss/es', whichever seems to fit the context better is fine. For 'core ...', you probably know the favoured choice/s best yourself. Commented Jul 3, 2015 at 8:41
  • would you say "less loss" or "fewer losses"?
    – Brad
    Commented Dec 24, 2015 at 10:58
  • "Copper losses" is already a bit off track, since that term implies that copper is being lost.
    – Hot Licks
    Commented Feb 18, 2016 at 0:47
  • I actually read that as copper being lost to be honest. Not in terms of an entire rail missing, but I can imagine that depending on the currents and other environmental variables that copper conductor has to deal with, the surface of the conductor might actually wear away over time.
    – Terah
    Commented Feb 25, 2016 at 16:25

3 Answers 3


When dealing with an electrical "inductor" the system will tend to lose energy due to various interactions with the resulting magnetic field, or due to resistance in the copper coil itself. The energy lost from the magnetic field is primarily lost in the "core" (which, in the simplest cases, is a bundle of iron strips).

So the two types of energy loss are due to the "core" and due to the "copper" -- "core losses" and "copper losses". (Note that the terminology does not imply that either "core" or copper is being "lost", but rather the mechanisms causing energy loss involve the "core" and the copper. This is plain old "jargon" within the electrical and electronics industry and, as jargon, is a perfectly legitimate phrasing.)

In particular, with the core there are several mechanisms at work -- primarily "hysteresis" and "eddy currents", but also a few others. So there is not a single factor causing the "loss", and hence the term "losses" is quite appropriate.

With the copper the mechanism at work is almost entirely plain old "ohmic" resistance in the copper wire, and the wire (for a simple inductor) is generally a single continuous piece of thin copper. So one might argue that there is only one "loss" involved. But then it would be weird to say "core losses and copper loss".

In summary, since this is, after all, jargon, "core losses" and "copper losses" are perfectly legitimate and justifiable terms.


Stating a mass noun in the plural (current losses, current flows, etc) implies that more than one example is being considered. This could be a spacial or temporal separation (of the losses). 'Loss' is clear for the net loss, but 'losses' is better when tallying the measurements.


Losses is always plural.

Loss can either be a mass noun or a count noun.

Your answer lies in the titles of those Wiki pages: Core Loss and Copper Loss. Whether they need be plural is context dependent. E.g.,

  • The copper loss of aluminum wire.

  • The copper losses of aluminum wire verses copper wire.

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