I Why is it that the fundamental harmonic is louder than rest?

And the fundamental does not have to be the loudest. You can excite the system such that the higher harmonics have larger amplitudes. Even with zero amplitude for the fundamental.
However the damping usually increases with frequency and after some time after the excitation, the higher harmonics die faster and the fundamental may dominate.

 

Your question prompted me to do some reading and it turns out that it's not always the case e.g. for some musical instruments such as the trumpet the higher harmonics have a larger amplitude.

 

I think that the fundamental is called that because it's the one you hear. If there are lower frequencies present and they are lower amplitude than the fundamental, they are called sub-harmonics. The amplitude is representative of the loudness, although loudness is a psychological phenomena in some cases.

 

The term fundamental has nothing to do with loudness. It is the lowest frequency mode of the system. The sub harmonics have lower frequencies. Amplitudes are not relevant for these definition.

 

It's not always. However, the overtones of any standing wave are usually the highest amplitude. The way the oscillations are matched to the air can bring out higher order overtones out more. I use the term Overtone because the higher orders may be far from harmonics. Brass instruments can be waaay out without the player pulling notes. But it's what we find pleasing.

 

What he was referring to was Quantum Mechanics. In particular, the formula
E = hf tells you the energy of a photon.

 

As sophiecentaur points out, the energy of a photon is proportional to the frequency of the light. The number of such photons determines the total energy at that frequency.

 

what kind of system are you referring to?

 

You need context. While energy can be related to energy, it is NOT the ONLY factor when considering the energy of a classical wave. The amplitude of the wave also affects the energy. So your physics lecturer is correct. However, you understood it as it being the only factor affecting energy.

Zz.

 

Actually, what is conserved is "power", the amount of energy going through a point in a unit time. It is why, for a light source with a fixed power, increasing the frequency will cause the intensity to drop, because there can only be a fixed amount of energy given off per second.

So while this is true in the case of refraction, you need to be clear that this is the case where there is a fixed amount of energy being given to start with. It is not true in ALL general cases. This is easy to see if you have 2 different spring-mass systems. Use the same mass, but use different spring constant k. Now let them oscillate with the same amplitude. Which one do you think will have more "energy"? Next, change the amplitude of each one of them. Do you think each one will have the same energy as before if I oscillate them with a different amplitude? After all, the frequency of oscillation for each one of them remains the same as before.

When you ask a question in this forum, it is imperative that you be very clear and concise. If it is related to something, or it is something you're thinking of in your head, don't assume that (i) we can read your mind and (ii) you have a general "rule" that will be true everywhere. When you are asking about something with a particular context in mind, you must reveal that context. Otherwise, we will be talking about chickens while you're thinking about cows.

Zz.