Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Induced EMF in house-hold WIFI

  1. Mar 5, 2014 #1
    Hi everybody,

    I was wondering how much induced EMF would be produced in a 20cm diameter coil with 100 loops produce. Has anyone conducted such an experiment?

    I am interested in quantitative values of the experiment.

  2. jcsd
  3. Mar 6, 2014 #2


    User Avatar
    Science Advisor
    Gold Member
    2017 Award

    welcome to PF

    not sure what you are trying to prove or achieve ??
    care to elaborate further ... explain your setup better

  4. Mar 9, 2014 #3
    The emf completely depends on the net magnetic flux passing through the coil (and how it's changing), and that in turn, depends on the environment the coil is suspended in. If you're in an active environment (next to a massive sub-station power transformer, the voltage could be in the millivolt range, but in a normal environment, it might be below the microvolt range. The diameter of the coil has nothing (directly) to do with the voltage. The voltage depends only on the number of turns and how fast the flux passing through the coil is changing (V = -N dø/dt). However, a larger coil might be more likely to intercept a greater amount of flux, increasing the dø/dt term of the equation and thus the coil voltage.

    Relative to Wi-Fi and the coil acting as an antenna, the voltage will depend on the orientation of the coil relative to the source, the strength and distance of the source, and also needs to take impedances and matching to the receiver load into account. Your question is pretty open-ended.
  5. Mar 9, 2014 #4


    User Avatar
    Science Advisor
    Gold Member
    2017 Award

    The limit of total power that may be radiated from a normal WiFi transmitter is significantly less than 1/10W. Any power you can couple into a receiving antenna (whatever shape you choose) is going to be considerably less than that (in the region of less than a milliWatt) unless the transmit and receive antennae are more or less touching)_

    There is a distinction between transmitting and receiving signals and transferring useful amounts of power, to drive a device.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook