Apparently Wi-Fi uses the battery on an iPhone true or false?

According to a friend

True.
Doing things on your phone uses battery, so therefore using it uses more power

Using Wi-Fi will increase battery usage, yes.

On all smartphones or iPod touches and stuff having Internet or Wi-Fi turned on WILL use up a bit of your battery. If you wanted you battery to last longer then turn the brightness down and Wi-Fi off and don't play games

Yes of course. Using 3G and Bluetooth use the battery charge faster too, also the higher the brightness on the screen will use it faster, to be honest though not matter what you do to save battery you'll still have to charge your phone at least once a day, I know I do

Yes, it's true, the more things you are using, e.g. Wi-Fi, Bluetooth, etc. The faster your battery will run out. When you are out and about, e.g. In a car, try to remember to turn it off, your battery should then last around 45% longer.

Absolutely yes, the sending and receiving data signals use the battery of your cell phone. The signal processing is done in your mobile phone that requires the battery for the technical procedures like coding, decoding, filtering, amplification ect.

I'm an engineering student so if you want to know more about it then I can tell you in detail.

Yes, this is true. Every function on a phone uses some battery to work. Apps, phoning, texting, everything.

It is true of any phone or gadget too.

True! Wi-Fi, Bluetooth and 3G All drain battery life and you should turn them on when not in use!
Hope this helps

Most definitely it does! All the time it's switched on, it is taking battery power by searching for Wi-Fi transmitters. Turn it off to save battery, when necessary.

Yes it does, also sound and brightness drains it too!