Valerie,
The conductors in the original photograph are a little bent/curved looking and I'd like them to be straighter.
I think Peter's and Mark's more detailed approach could work. However, I'm not certain the wires need to be straightened. The slight bends make them look more "real".
If I had much work that required corrections like this, which amount to precise morphs of the image that require more accurate control than Photoshop's Liquify can deliver, I would get Human Software's Squizz <
http://www.humansoftware.com/pages1200/Squizz/HSsquizz11.htm l>. Squizz has several ways to morph, transform, or distort an image or part of an image.
In your case with the bent wires you would use Squizz's Advanced Grids feature <
http://www.humansoftware.com/pages1200/Squizz/HSsquizz1111.h tml>. That feature can also be used to straighten a distorted image <
http://www.humansoftware.com/pages1200/Squizz/HSsquizz1114.h tml>, and you could use it in that way to straighten the wires. You would draw a gridline along the centerline of a bent wire and then simply straighten that gridline to straighten the wire. That gives you a degree of control that you can't get with Liquify. And by simply morphing the original wires you avoid getting any "fake" look from pasted on wires.
-- Burton -- (not associated with Human Software or Squizz!)