Water Taps are actually airtight!

Have you ever tried fitting an inflated balloon on a tap's mouth?
If no, then you should try! You might have thought it's impossible to fit a balloon on a tap's mouth but it's possible!

Method (pretty simple, you could actually figure it out yourself)-

What all you need-

A relatively big balloon
A water tap which works
And an air pump for filling up your balloon

Method Again-

Fill the balloon with as much as air as you can (don't let it burst), and slowly press the are under the outlet of the balloon and fit it to the tap, you can let some air out while you're doing so. Bingo! You'll see that there isn't a bit of air getting of your balloon. Here's why-

Bulb On?
It's a very, very simple definition, and the reason is something which occurs almost everyday in our life.

This phenomenon may not occur in water - less taps, as this resistance to air pressure is mainly due to water, unless you have got a really high tech tap, which is airtight in all circumstances. Maybe a lab tap.