Production of electromagnetic waves?
Can i ideally produce all these electromagnetic waves of different frequencies by changing the frequency of current/voltage to the conductor ? 


That is necessary, but not sufficient: your conductor must be designed to radiate. That's why antennas have a specific shape. Typically, an antenna is somewhere between ¼ and a full free-space wavelength of the radiated wave; but that's really just a very general rule of thumb. Some antennas can be made much smaller, others are built much larger for complex engineering reasons.


  How the frequency of the electromagnetic waves is related to the frequency of the alternating current in the conductor ?


They are one and the same.


  Is there any equation that relates the two frequencies ?


\$f_\text{current} = f_\text{wave}\$. No magic here.


  Or simply to generate the electromagnetic wave of 8×10^14 Hz (light), i will have to oscillate the charges with the frequency of 8×10^14 Hz in the conductor ?


In principle, yes. But:

It's technically impossible to do that with what you think of when you think of AC sources. 

Instead, light is emitted, for example in LEDs, when electrons need to lose energy. Sadly, you're leaving the realm of Maxwell's equations (which describe electromagnetism on any non-quantum-sized scale), and enter the world of solid state quantum physics. So, while it would work that way, if you could find something fast enough to work as a source of AC, but smaller than the wavelength of light … which doesn't happen; metal material with conduction bands quickly becomes larger than that, and the properties of semiconductors and electron gases simply aren't very similar to what we're used to at lower frequencies. I can't build a \$10^{14}\,\text{Hz}\$ oscillator; effects that are very benign and irrelevant at lower frequencies dominate here, and none of our electronics still work like they should.


  Or all these electromagnetic waves will be produced in any other different ways ?


Yes. You probably have heard of light sources before: candles, incandescent lamps, LEDs and lasers, among a couple other things.

You're deep into the world of photonics here.