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प्रश्न
A laser beam has intensity 2.5 × 1014 W m−2. Find amplitudes of electric and magnetic fields in the beam.
उत्तर
Given:
Intensity, I = 2.5 × 1014 W/m2
We know :
`I = 1/2 ∈_0 E_0^2 c`
⇒ `E_0^2 = (2I)/(∈_0c)`
⇒ `E_0 = sqrt((2I)/(∈_0c))`
⇒ `E_0 = sqrt((2 xx 2.5 xx 10^14)/(8.85 xx 10^-12 xx 3 xx 10^8))`
⇒ `E_0 = 0.4339 xx 10^9`
⇒ `E_0 = 4.33 xx 10^8 "N/C"`
Maximum value of magnetic field ,
`B_0 = (E_0)/c`
`B_0 = (4.33 xx 10^8)/(3 xx 10^8)`
⇒ `B_0 = 1.43 "T"`
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