A laser beam has intensity 2.1 times 10^{15} | vedclass

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(B) The intensity $I$ of an electromagnetic wave is related to the amplitude of the magnetic field $B_0$ by the formula: $I = \frac{B_0^2}{2 \mu_0} c$

Vedclass · Accepted Answer

$4.2$

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(B) The intensity $I$ of an electromagnetic wave is related to the amplitude of the magnetic field $B_0$ by the formula: $I = \frac{B_0^2}{2 \mu_0} c$. Given: $I = 2.1 	imes 10^{15} \ W/m^2$,$c = 3 	imes 10^8 \ m/s$,and $\mu_0 = 4 \pi 	imes 10^{-7} \ T \cdot m/A$. Substituting the values: $2.1 	imes 10^{15} = \frac{B_0^2 	imes 3 	imes 10^8}{2 	imes 4 \pi 	imes 10^{-7}}$. $2.1 	imes 10^{15} = \frac{B_0^2 	imes 3 	imes 10^8}{8 \pi 	imes 10^{-7}}$. $B_0^2 = \frac{2.1 	imes 10^{15} 	imes 8 \pi 	imes 10^{-7}}{3 	imes 10^8} = \frac{16.8 \pi 	imes 10^8}{3 	imes 10^8} = 5.6 \pi \approx 5.6 	imes 3.14 = 17.584 \approx 17.64$. $B_0 = \sqrt{17.64} = 4.2 \ T$.

$A$ laser beam has intensity $2.1 \times 10^{15} \ W/m^2$. The amplitude of the magnetic field in the beam is approximately: (in $T$)

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