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The +M effect, also known as the positive mesomeric effect, occurs when the substituent is an electron donating group. The group must have one of two things: a lone pair of electrons, or a negative charge. In the +M effect, the pi electrons are transferred from the group towards the conjugate system, increasing the density of the system.
Ferroresonant effects were first described in a 1907 paper by Joseph Bethenod. [ 3 ] [ 4 ] The term ferroresonance was apparently coined by French engineer Paul Boucherot in a 1920 paper, in which he analysed the phenomenon of two stable fundamental frequency operating points coexisting in a series circuit containing a resistor, nonlinear ...
The Mössbauer effect, or recoilless nuclear resonance fluorescence, is a physical phenomenon discovered by Rudolf Mössbauer in 1958. It involves the resonant and recoil -free emission and absorption of gamma radiation by atomic nuclei bound in a solid.
Helmholtz resonance, also known as wind throb, refers to the phenomenon of air resonance in a cavity, an effect named after the German physicist Hermann von Helmholtz. [1] This type of resonance occurs when air is forced in and out of a cavity (the resonance chamber ), causing the air inside to vibrate at a specific natural frequency .
The damping force ensures that the oscillator's response is finite at its resonance frequency. For a time-harmonic driving force which originates from the electric field, Newton's second law can be applied to the electron to obtain the motion of the electron and expressions for the dipole moment , polarization , susceptibility , and dielectric ...
To cause resonance, the phase of a sinusoidal wave after a round trip must be equal to the initial phase so the waves self-reinforce. The condition for resonance in a resonator is that the round trip distance, 2 d {\displaystyle 2d\,} , is equal to an integer number of wavelengths λ {\displaystyle \lambda \,} of the wave:
Resonance fluorescence is the process in which a two-level atom system interacts with the quantum electromagnetic field if the field is driven at a frequency near to the natural frequency of the atom.
In physics, a Feshbach resonance can occur upon collision of two slow atoms, when they temporarily stick together forming an unstable compound with short lifetime (so-called resonance). [1] It is a feature of many-body systems in which a bound state is achieved if the coupling(s) between at least one internal degree of freedom and the reaction ...