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  2. Tuning fork - Wikipedia

    en.wikipedia.org/wiki/Tuning_fork

    Tuning fork pitch varies slightly with temperature, due mainly to a slight decrease in the modulus of elasticity of steel with increasing temperature. A change in frequency of 48 parts per million per °F (86 ppm per °C) is typical for a steel tuning fork. The frequency decreases (becomes flat) with increasing temperature. [6]

  3. Optical chopper - Wikipedia

    en.wikipedia.org/wiki/Optical_chopper

    To be effective, an optical chopper should have a stable rotating speed. In cases where the 1/f noise is the main problem, one would like to select the maximum chopping frequency possible. This is limited by the motor speed and the number of slots in the rotating disc, which is, in turn, limited by the disc radius and the beam diameter.

  4. Acoustic resonance - Wikipedia

    en.wikipedia.org/wiki/Acoustic_resonance

    Experiment using two tuning forks oscillating at the same frequency.One of the forks is being hit with a rubberized mallet. Although the first tuning fork hasn't been hit, the other fork is visibly excited due to the oscillation caused by the periodic change in the pressure and density of the air by hitting the other fork, creating an acoustic resonance between the forks.

  5. Hubble sequence - Wikipedia

    en.wikipedia.org/wiki/Hubble_sequence

    Roughly half of all spirals are also observed to have a bar-like structure, with the bar extending from the central bulge, and the arms begin at the ends of the bar. In the tuning-fork diagram, the regular spirals occupy the upper branch and are denoted by the letter S, while the lower branch contains the barred spirals, given the symbol SB.

  6. Electromagnetic spectrum - Wikipedia

    en.wikipedia.org/wiki/Electromagnetic_spectrum

    In frequency (and thus energy), UV rays sit between the violet end of the visible spectrum and the X-ray range. The UV wavelength spectrum ranges from 399 nm to 10 nm and is divided into 3 sections: UVA, UVB, and UVC. UV is the lowest energy range energetic enough to ionize atoms, separating electrons from them, and thus causing chemical reactions.

  7. Spectral resolution - Wikipedia

    en.wikipedia.org/wiki/Spectral_resolution

    The spectral resolution of a spectrograph, or, more generally, of a frequency spectrum, is a measure of its ability to resolve features in the electromagnetic spectrum.It is usually denoted by , and is closely related to the resolving power of the spectrograph, defined as =, where is the smallest difference in wavelengths that can be distinguished at a wavelength of .

  8. Sympathetic resonance - Wikipedia

    en.wikipedia.org/wiki/Sympathetic_resonance

    In similar fashion, strings will respond to the vibrations of a tuning fork when sufficient harmonic relations exist between them. The effect is most noticeable when the two bodies are tuned in unison or an octave apart (corresponding to the first and second harmonics , integer multiples of the inducing frequency), as there is the greatest ...

  9. Melde's experiment - Wikipedia

    en.wikipedia.org/wiki/Melde's_experiment

    In this experiment the change in frequency produced when the tension is increased in the string – similar to the change in pitch when a guitar string is tuned – will be measured. From this the mass per unit length of the string / wire can be derived. This is called as the principle of the Melde's Experiment