Can i use my ipad 2 charger to my iphone 4?

I'm just worried if there's a bad effect on my phone

They are compatible

Yes. The Apple web site lists the 10W charges as being compatible with the iPhone 4.

Hope this helps!

Yup you can. Ipad I phone ipod imac all have the same charger and none hurt anything. It's just a wire that they all use.

As of right now, all iphone chargers are the same for the pads and pods.