Hello, this is my first post on these forums, and I hope to get a response. I am doing an experiment about building a type of an amusement park ride on a much smaller scale, and I have some questions and need some advice. Firstly, when I make an electromagnet by wrapping a piece of metal with a wire, and then run a current through the wire, how strong can the magnetic field be? I know it depends on the current but how man volt would i need to make the field strong enough to pull a very heavy metal. say around 3-5kg. What if I wrap the wire around a magnet? would that be stronger? Second I need something like a transformer which can alter the flow of the current regularly, for ex. if the current coming in is around 30 V. I need something which can regulate it regularly. What type of a mini transformer can I use? I want that transformer to be such that it should be a sort of a button, the harder I press the more volt it should let pass, and if I don't press it at all then it should pass almost none. Is it possible that I build this device myself, can I get instructions? Thirdly I need to know how can I create an AC generator. So let's say it can change the current continuously at a rate of around 1 second, or any other time which would be more sufficient. Fourthly if I want to build a sort of a banner that would go up and down. Suppose I want to use a solenoid, nothing else. And it should go up and down withing one second. Suppose the tube is 14 inches long. I wrap it with a wire, place a thick steel rod suppose of 1.5 inches. Inside the rod I place a strong magnet, so the rod would go in and out of the tube with a lot of force.I would attach the rod with the tube in such a way that it isn't shot out. then it moves back in by reversing the current. How do I do this, and is using a solenoid a good idea? I'm sure such problems are common here on this forum. But since I don't know a lot about physics, I need to know this information.