MacBook – Water resistant MacBook or Air

In general - drops will not find the sensitive places and unless you live in an area with salt spray saturating the air - it won't gather much salt and be corrosive before it dries.

Statistically, there are only a few places where water will get wedged into a small crack (capillary action also can move a drop quite some distance from where it lands) and cause corrosion before it evaporates.

You did well to power it off. The only other thing would be to flip it upside down after closing a cloth between the keys and the screen.

You can edit your question to specify exactly where the liquid landed and what model (year and size) and I'll see if you need any more details in the answer.

In short - don't worry. Let the water dry, and use the Mac. Take it in to a genius bar or someone well used to repairing that mac. They will be able to educate you on the risks of using it (not much - and back up your data anyhow - something will eventually fail spills, accidents or perfect maintenance nonetheless).

The reason it's brighter is because water has a refraction index that is closer to 'glass' (as in the specific material used in the screen--I know it's not really glass per se) than air does. This means that less light is lost in the area between the LCD and the front glass (or between the LCD and the backlight--but not very likely) and thus the screen appears brighter.

You'd probably get a better explanation on Physics in terms of specifics, but this is the answer in a nutshell.