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Q & A: Can light induce a voltage in a coil?

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Most recent answer: 06/04/2015
Q:
As per Faraday's Law, "Any change in the magnetic environment of a coil of wire will cause a voltage (emf) to be induced in the coil". A light wave has both a periodically changing electric and a magnetic field associated with it. Why then does no voltage get induced in a coil that is exposed to light?
- Sandeep Sharma (age 39)
Dallas, TX
A:

Hi Sandeep,

In principle, yes.   For example a solenoid antenna can pick up an FM radio broadcast due to induction. However the frequency of light is so high and the wavelength so short that it would be impractical to build a coil that would detect it. The induced signal would be at the same frequency as the light and the dimensions of a pickup coil should be of the same order of magnitude as that of the light wavelength.  

LeeH


(published on 06/04/2015)

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