Question

A plane electromagnetic wave, has frequency of 2.0 × 10¹⁰ Hz and its energy density is 1.02 × 10^–8 J/m³ in vacuum. The amplitude of the magnetic field of the wave is close to (${1\over4\pi\varepsilon_0}=9\times10^9{Nm^2\over C^2}$ and speed of light = 3 × 10⁸ ms^–1) : 

(1) 160 nT 

(2) 180 nT 

(3) 190 nT 

(4) 150 nT 

Comments

Electromagnetic waves

Answer 1

Ans : (1) 160 nT

Explanation: 

Comments

How did you knw to use this formula ?

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there is only one formula magnetic energy density