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A 27 mW laser beam has a cross-sectional area of 10 mm 2 . The magnitude of the maximum electric field in this electromagnetic wave is given by : [Given permittivity of space ∈ 0 = 9 × 10 –12 SI units, Speed of light c = 3 × 10 8 m/s]

1. 2 kV/m
2. 1 kV/m
3. 1.4 kV/m
4. 0.7 kV/m

Correct answer: 1.4 kV/m

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