# What is the minimum wave length of EM waves that can generate electricity?

#### PlasmaT

Joined Feb 19, 2015
61
Just wondering, since visible light and radio waves are both electro-magnetic waves, why cant light induce electricity by induction? Is there a limit to the wave length that can induce electricity?

#### LDC3

Joined Apr 27, 2013
924
There probably is no limit for radio waves inducing currents in antennas.

I think the problem with the very high frequencies is designing an amplifier with very low capacitance. If you cannot amplify the signal, there is no point in using that frequency.

When electricity started to be delivered, line frequencies as low as 16 Hz was used. This means that a 16 Hz radio signal would also induce currents in antennas.

#### crutschow

Joined Mar 14, 2008
25,647
Light has such a short wavelength that it doesn't penetrate a conductor so can't induce a current in them.
To generate a current you need a material that can absorb the light short wavelength and generate a current, such as a doped semiconductor junction, thus giving us solar cells.

The nominal point where standard electrical conductors don't work well for inducing electrical currents is somewhere in the terrahertz region. That's why there is little practical electronics in this region although much experimental work is being done there.
For comparison visible light goes from 470THz to 790THz.

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#### alfacliff

Joined Dec 13, 2013
2,458
Light has such a short wavelength that it doesn't penetrate a conductor so can't induce a current in them.
To generate a current you need a material that can absorb the light short wavelength and generate a current, such as a doped semiconductor junction, thus giving us solar cells.

The nominal point where standard electrical conductors don't work well for inducing electrical currents is somewhere in the terrahertz region. That's why there is little practical electronics in this region although much experimental work is being done there.
For comparison visible light goes from 470THz to 790THz.
werent iron plates in sunlight used to prove some of Einsteins throeirs about photovoltaic effect? light wont penetrate iron very far, if at all.