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Photometry and Geometrical Optics

Problem 5.2

A point isotropic source emits a luminous flux Φ=10 lm\Phi=10 \mathrm{~lm} with wavelength λ=0.59μm.\lambda=0.59 \mu \mathrm{m} . Find the peak strength values of electric and magnetic fields in the luminous flux at a distance rr =1.0 m=1.0 \mathrm{~m} from the source. Make use of the curve illustrated in Fig. 5.1 .

Reveal Answer
 5.2. Em2=Vμ0/ε‾0AΦ/2πr2Vλ, hence Em=1.1 V/m,Hm= \text { 5.2. } E_{m}^{2}=V \overline{\mu_{0} / \varepsilon}_{0} A \Phi / 2 \pi r^{2} V_{\lambda}, \text { hence } E_{m}=1.1 \mathrm{~V} / \mathrm{m}, \quad H_{m}= =3.0 mA/m.=3.0 \mathrm{~mA} / \mathrm{m} . Here A=1.6 mW/lm,VλA=1.6 \mathrm{~mW} / \mathrm{lm}, V_{\lambda} is the relative spectral response of an eye for the given wavelength.
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