What are the requirements for volunteering in a hospital? And what are some typical jobs of a volunteer?

Hi! I'm really interested in volunteering at my local hospital this summer to get an idea about how it might be like working there. I thought it would be a great way to learn, (I'd like to become a nurse when I'm older) and also a great way to get my community service hours done, because my high school requires 40 hours of community service to graduate. I just wanted to know what kinds of jobs I'd be doing if I volunteered at a hospital, and some of the requirements. Such as how old I would have to be. I'm a freshman in high school, and I'm fifteen. Would that be old enough? I'm really curious, and I'd love to volunteer!