calculate the electric and magnetic fields produced by the radiation coming from a 100 watt bulb at a distance of 3m with efficiency of 2.5 % and it is a point source

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The surface area of surrounding of sphere is,A=4πr2A=4×3.14×32=113 m2The intensity at this distance is,I=PowerAreaI=100×2.5%113I=100×2.5100×113=0.022 W/m2Half of the intensity is provided by the electric field and half by the magnetic field.12I=12ε0Erms2c0.022=ε0Erms2cErms=0.0228.85×10-12×3×108Erms=2.9 V/mSince the electric field in a light beam is sinusoidal, the peak electric field is,E0=2ErmsE0=2×2.9=4.07 V/mNow, Brms=ErmscBrms=2.93×108=9.6×10-9 TAgain, Since the field in a light beam is sinusoidal, the peak magnetic field is,B0=2BrmsB0=2×9.6×10-9=1.4×10-8 T

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