If you think of how waterproof an electronic device is in relation to a free body diagram, at what force/psi is the water trying to get in at the seems of the device, for example a phone.

Question

In other words, what’s the force required at a seem or between two flat surfaces to make a device waterproof?

Also, im assuming that as you dive deeper under water, the force of the water seeping into the phone increases, but is there some sort of function/equation to predict that increase?

I understand that waterproof seals are a simple concept, but my intention is to understand all the forces at play in a mathematical way.

In: Physics

Answer 1

Water has sumface tension that sucks it into narrow structures. You can see this with a thin tube in water, like in [this pic](https://www.usgs.gov/media/images/narrower-tube-openings-allow-capillary-action-pull-water-higher ).

Answer 2

Just a point, most electronics, such as mobile phones are not sealed waterproof systems like you if you think of a waterproof box– thats not what the phone is, and most “waterproof” electronics are not that. (Also, its better to refer to them as water resistant, not water proof)

Instead, for stuff like mobile phones, they have water resistant coatings over the electronics that provide some resistance to water damage

Answer 3

The pressure in Pascals at a given depth in a liquid is given by:

Pressure = depth × density × gravitational field strength(g)

For water density is 1000 (because this is in kg per cubic metre, not grams per cubic centimetre).
For Earth g is 9.81.