I guess you could say a few things about the variation of the light spectrum as you took a light bulb from zero volts up to about 150% of its rated voltage. It's mainly hot body radiation variations once the filament starts to glow.cscott said:Would "How does the frequency spectrum of a light bulb varry with the voltage across it." be valid?
I guess you could say a few things about the variation of the light spectrum as you took a light bulb from zero volts up to about 150% of its rated voltage. It's mainly hot body radiation variations once the filament starts to glow.
cscott said:Berkman, can you explain a bit more? Would there be enough change in the spectrum to be worth the experiment as a project? Will only the magnitudes change? What about with light bulb dimmer switches? Or dimmer switches with fluorescent light bulbs?
berkeman said:The spectrum of "black body radiation" changes with the temperature of the object:
http://en.wikipedia.org/wiki/Black_body_radiation
George Jones said:How do the Fouier components of a musical note affect the sound of a note?
One of the reasons differenet musical instruments sound different when playing the same (sustained) note is because of the different components present, and and because of different relative strengths of the various components.
Regards,
George
What else do you see on the two spectra?cscott said:Our FFT graphs show the same obvious spikes (for instance, ~165 Hz when playing E3) but electric still doesn't give the same "sound" as an acoustic.
berkeman said:What else do you see on the two spectra?
That's a good item to consider. What would be best would be to calculate the spectra of each instrument as a function of time. That's a different kind of signal processing than just taking the Fourier transform of a long waveform to see it in the frequency domain instead of the time domain. A Fourier Analyzer (I think that's what they are called) analyzes the energy in many sub-spectra bands all at the same time. Kind of like you see with a bar graph display of an audio spectrum -- each one of the bar graphs is basically a narrow bandpass filter of a portion of the spectrum.cscott said:I've been trying to brush up on general sound theory to perhaps get some ideas. What about something like the differences in http://www.sfu.ca/sca/Manuals/ZAAPf/a/acoustic_env.html?
Fourier Analysis is a mathematical technique that breaks down a complex signal or function into simpler components. It is used in experiments to analyze and understand the different frequency components of a signal, which can provide insights into the underlying processes or phenomena being studied.
Any experiment that involves measuring or analyzing a signal can benefit from Fourier Analysis. This includes experiments in physics, engineering, biology, chemistry, and many other fields. Common examples include analyzing sound waves, electrical signals, and physical vibrations.
The basic steps involve first collecting a signal or data, then performing a Fourier transform to break it down into its frequency components, and finally analyzing the results to gain insights into the underlying processes or phenomena. This may also involve applying filters or other techniques to isolate specific frequency components.
Some potential sources of error or limitations include noise in the signal, aliasing (when the highest frequency in the signal is greater than the sampling rate), and assuming that the signal is stationary (does not change over time). Additionally, the results may be affected by the windowing function used in the Fourier transform.
Yes, there are other mathematical techniques such as wavelet analysis, which also break down a signal into different components. Additionally, some signals may require specialized techniques specific to their properties and characteristics. It is important to carefully consider the specific needs of the experiment when choosing an analysis method.