Why is it bad to take a loop of wire and connect a positive battery terminal to a negative terminal?

Which branches of natural science include the study of an organism that lived 10 million years ago

The star betelgeuse is about 600 light-years away. if it explodes tonight, a. we'll know because debris from the explosion will rain down on us from space.b. we'll know it immediately because it will be brighter than the full moon in the sky.c. we won't know about it until 600 years from now.d. none of the above.

What is the increase in density of a medium due to wave travel?