\(\text{Energry} \propto \text{Intensity} \propto (\text{Amplitude})^2\)
If there is no friction:
In 3D, the energy spreads on an expanding spherical shell at the speed of the wave. So \(\text{Energy} \propto 1/r^2\). Example, light from sun, or sound from a plane.
In 2D, the energy spreads on an expanding ring. So \(\text{Energy} \propto 1/r\)
In 1D, the energy never dissipates! Example, wave created by snapping a rope.
When a wave travels from rarer to denser medium, the phase of reflected wave shifts by 180\(^\circ\).
When a wave travels from denser to rarer medium, the phase of reflected wave remains the same.
The transmitted wave does not undergo any phase shift.
Speed of wave depends on property of the medium it is travelling in. It does not depend on frequency, or amplitude.
Speed of sound in metals is more than liquid, which is more than in gas. More dense the medium the faster the speed of sound. (The more rigid/dense, more the speed).
Speed of sound is faster at higher temprature. (The higher the temperature, the faster the molecule can reach other molecule and transfer their energy)
\(f\) is the frequency of photon.
Other relations like: \(\boxed{E = {hc\over{\lambda}}\;\;}\) can be derived using wave property, \(\boxed{c = \lambda f \;\;}\) and for photon \(\boxed{E = cp\;\;}\) p is momentum, E is the energy.
When Max Plank said, the light behaves like particle, De-Broglie said, particle may also behave like wave given by:
Einstien gave this formula:
It is really conservation of energy equation of the phenomenon, where:
Interesting Facts