How to know if the the iphone charger or the phone?

Well, my original iPhone 4S charger was Brocken and I got a new one from asda, awhile ago btw I only got my iphone in July so now it isn't working and when I connect it to my phone it makes a buzzing noise? Does this mean it's the charger or is it the phone? And which way could I know with out buying a new charger? Is the just the charger and am I worrying over nothing?

If your iPhone is charging you should see a charging icon on your battery at the top right.