Does a photo-resistor create an AC current?

AI Thread Summary
A photoresistor cannot create an alternating current (AC) as it only changes resistance based on light levels and does not produce an alternating effect. While it can vary current levels, it does not generate negative current or respond quickly enough for high-frequency applications. Achieving an AC frequency in the range of light is not feasible with a photoresistor, and typical electrical devices like photodetectors respond to light amplitude rather than frequency. Suggestions for generating high-frequency AC include using a radio transmitter or appropriate electrical components like LEDs, but these do not produce actual AC currents at light frequencies. Overall, the discussion emphasizes the limitations of photoresistors in generating high-frequency AC and the challenges in achieving such frequencies with standard devices.
grahas
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I'm a high school physics student. I want to do an experiment to see what happens when a high frequency alternating current goes through a magnet. To create the high frequency alternating current could a photo resistor do that for me? Does the photo-resistor create an alternating current with a frequency equal to the light hitting it?
 
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No, a photoresistor can only change the value of its resistance depending on the light level, and the frequency of the light doesn't produce an alternating effect.

You could vary between lower current and higher current with a photo resistor and a battery, but that's not exactly what you're asking for (the current would never go negative). Furthermore, I don't even think photoresistors respond quickly enough to alternate the current at even moderate frequencies.
 
Is there any way to achieve an alternating current with a frequency in the range of light, via a mechanical or electrical device?
 
Not to my knowledge. The frequency of light is much, much bigger than, say, microwave frequencies.
 
Well, I'll post back the results of my experiment to close the thread, thanks for the help!
 
grahas said:
I'm a high school physics student. I want to do an experiment to see what happens when a high frequency alternating current goes through a magnet

Are you saying you want to use the magnet as a conductor? I don't think anything is going to happen. What would you like to see happen?

As for high frequency AC, your wifi network runs at 2.4GHz. Low frequency (red) light is 400,000 GHz.
http://www.laserfocusworld.com/articles/print/volume-49/issue-07/newsbreaks/world-s-fastest-photodetector-has-70-ghz-bandwidth.html
Photodetectors respond to the amplitude of the light, not the light frequency

Nothing electrical directly responds at the frequency of light.
 
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meBigGuy said:
Are you saying you want to use the magnet as a conductor? I don't think anything is going to happen. What would you like to see happen?

other than short circuiting the power supply :wink:

to the OP ... definitely not a wise thing to do
 
grahas said:
Is there any way to achieve an alternating current with a frequency in the range of light, via a mechanical or electrical device?

A radio transmitter does that. Just put your magnet next to a cell phone while talking.

What effects would you see? Probably nothing.
 
grahas said:
Is there any way to achieve an alternating current with a frequency in the range of light, via a mechanical or electrical device?

yes, the standard way is to apply the correct amount of voltage to an appropriate light globe or LED ( Light Emitting Diode)
 
  • #10
davenn said:
yes, the standard way is to apply the correct amount of voltage to an appropriate light globe or LED ( Light Emitting Diode)
Note that does not actually create a 400,000 GHz AC current (electron flow). It creates a stream of photons with a frequency of 400,000 GHz
 
  • #11
meBigGuy said:
Note that does not actually create a 400,000 GHz AC current (electron flow). It creates a stream of photons with a frequency of 400,000 GHz

yes, I realize that ... but it's about the closest he is going to get :wink::rolleyes:
 
  • #12
I got it, and was sure you knew. Just wanted him to be clear.
 
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  • #13
meBigGuy said:
I got it, and was sure you knew. Just wanted him to be clear.

:smile:

grahas said:
Is there any way to achieve an alternating current with a frequency in the range of light, via a mechanical or electrical device?

I'm not aware of any way to do what he is asking. Even in the GHz microwave bands above around 30 GHz and up to several 100 GHz,
any oscillation within a Gunn diode or similar device, doesn't as an oscillation of electrons at that freq occur outside the device ( to my knowledge)Dave
 
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