Infrared Cameras

Congratulations, your plan worked! The mama bear chased after its missing cub and ran into the poachers just as you passed them. You didn't stick around to see the carnage, but from what you heard, you know that the angry bear has taken care of the poachers.

Before leaving the island in the poachers' boat, you want to set up infrared cameras in the cave to study the dwarf island bears. You want to place the cameras at even intervals throughout the 500 m long tunnel. You have 10 cameras and 2000 m of cable. If each camera needs a single length of cable connected to your computer at the entrance, how many cameras can you set up inside the cave? Note that you will have one camera all the way at the end of the tunnel but you can use the camera built into the computer for the entrance.

Hint:  If you type "sum n/x (n=1 to x)" into Wolfram Alpha you get this very useful equation: