For one thing, hydrogen gas or fuel is really expensive compared to present diesel and gasoline. There's no point in actually investing in them since economy will not improve otherwise. Gasoline stations will also have to adjust to how tricky hydrogen gas will be to support and store with ease. It's dangerous also to the driver, passengers and our environment.
The simple, immediate answer is: Because the public hasn't shown any interest in it yet.
That's why nobody is manufacturing and selling them yet ... there is no line out the door and around the block of buyers with fists full of cash looking for hydrogen fuel-cell cars.
To find what you're actually asking for, we have to look one layer deeper. WHY is there no market for such a car yet ?
-- If you want it, then they build it. But they will be built in small numbers, so they'll be expensive for quite a while.
-- The fuel distribution infrastructure doesn't exist. In high school English, that means that if you drove one of these, you'd always need to plan your moves carefully and in advance, because there are hardly ANY hydrogen filling stations yet. There's NO place in the USA yet where you'll see four hydrogen stations on the same corner, all competing for your business and all making a decent living.
-- There's also no fuel manufacturing infrastructure ... no hydrogen refineries, where the stuff would come from IF a thousand filling stations sprang up tomorrow. So the stuff will become available little-by-little, and when it begins to appear, you'll need to be really really committed to the idea of the fuel-cell car that you just bought, because the price of the fuel will be astronomical for a long time.
-- The existing big "energy" companies ... the ones with names that everybody recognizes right away, that rhyme with DT, Loyal Clutch Smell, DrexonFrobil, Howdy Salamco, Levron, MonacoPhllipo ... as well as the several WHOLE COUNTRIES that make their living from the Billion$ and Ten$ of Billion$ that they've plowed into finding, drilling, pumping, pipelining, and refining petroleum, and then delivering, pumping and selling gasoline at the thousands of filling stations ... those guys are not exactly encouraging the world to go after a new fangled idea that'll eventually put oil out of business.
When the population of the world basically rises up and demands hydrogen fuel-cell cars, loudly enough so that the big oil guys can't resist it any longer without looking like crooks, THAT's when they'll do the big turnaround, start insisting that the fuel cell is the best thing for us since fruit, and that it was really their idea all the time.
This is not something that waves do because they need a medium to travel through, while particles do not.
<h3>How light travels in space?</h3>
A light travels without any medium while on the other hand, a medium is required for sound waves to move from oe place to another. Sound is a mechanical wave that cannot travel through a vacuum.
So we can conclude that electromagnetic waves like light do not require medium for its propagation.
Explanation: For the first case we have to use the Balmer series for the hydrogen when the atom falls from the n = 3 to the n = 2. So for the second transtions for the hydrogen we use the Paschen serie. To do the calculation we need to know the Ryberg constant that is equal to 1.097 * 10^7 m^-1. In the attach is shown the expression for spectral series used for calculation.
