"How can you tell the charge on the VanDer Graf generator is - ?"
To determine the charge on a Van de Graaff generator, you can use a simple method involving a small object like a piece of paper or a small metal object. Here's how you can do it:
1. Start by turning on the Van de Graaff generator and letting it build up charge.
2. Take a small piece of paper or a small metal object, such as a paper clip or tiny aluminum foil ball.
3. Bring the object close to the sphere of the generator, but without making contact.
4. Observe the movement of the object. If the paper or metal object is attracted to the sphere and moves towards it, the charge on the generator is opposite to the charge of the object. In this case, the charge on the generator is negative.
5. If, on the other hand, the object is repelled and moves away from the sphere, the charge on the generator is the same as the charge of the object. In this case, the charge on the generator is positive.
It's important to note that the Van de Graaff generator can build up a very large amount of charge, so use caution and follow safety instructions when performing any experiments or tests.