# Unknown Circuit Symbol

What are these circuit symbols (circled in red) in these diagrams?

I am studying high school introductory physics, and this image is from a problem on circuitry in my online course. The problem is unrelated to the meaning of these particular symbols, but I am curious and would like to know.

• Symbol with +/- is a "rotating machine" with commutator or (seems less likely) slip rings. Jul 27, 2015 at 11:27

The bottom symbol in B is a fairly common symbol for a motor.

The other one seems to be an uncommon symbol for a generator. This page identifies it as a DC generator:

http://avstop.com/ac/apgeneral/basiccircuit.html

http://www.electronic-symbols.com/electric-electronic-symbols/electric-generator-symbols.htm

Both pages are missing the + and - signs. The presence of + and - signs and the overall context suggest it's meant as a DC generator, or (less likely) a generic voltage source.

Unfortunately, as my links show, there's not a lot of consistency in these kinds of symbols.

• The "AC power" (not "AC generator") symbol in your second link is missing the +/- annotations included in the OP's diagrams. Of course, so is the one in the first link, but it references it with a annotated DC generator. Jul 27, 2015 at 20:54
• Thanks for the links to different sources. I'm learning that circuit symbols are rarely consistent! Jul 31, 2015 at 3:47

DC generator (x 4) and DC motor (x 1).

Adam Hauns answer is mostly right, but both references say dc generator, ac generators does not have +-, while dc does.

It appears that the circuits are given as possible answers to a problem. If this is the case, (A) is not a valid answer. If (B) is correct, you have a DC generator and a DC motor connected in series. If (C) is correct, you have a DC generator acting like a DC motor because it is connected to a battery. If (D) is correct, you have a DC generator connected to a lamp, and its current is being measured.

• ??? (A) Generated power heats resistor, (B) Generator drives motor, (C) Generator charges battery, and (D) as stated above. They all work for me :) Jul 30, 2015 at 22:31