Determining the weight of a counterfeit coin?

Bob found a pile of 50 golden dollars, along with a note stating that one of them is counterfeit and the only way to tell the weight difference is by weighing them.

1. If Bob uses a balance scale, what is the least number of times he must weigh the coins in order to determine which is the counterfeit coin?

2. Describe two different ways this could be done.

I think the answer to #1 is 2, because you can divide into two groups of 24, then, assuming they balance, weigh the remaining two to get your answer. However, I can’t come up with a second way for how two weighings could be done.