Dim photos taken by iPhone 5?

My iPhone 5 takes good photos when there's no darkness. If I take photos in a place that is not well-lit as in the muesum today, the photos are dim, although the flash works.So, what should I do to get the same good quality photos?

Taking photos requires light - the iPhone does a considerable job of adapting from ordinary inside lighting as in a home or classroom to the very bright outdoor lighting of summer sunshine - but the flash only reached about as far as a person standing in front of you and if you are expecting it to fill a large room that is not well lighted you will get grainy, dark, blurred pictures with any camera that isn't mounted on a tripod for a longer exposure.