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]

a. |
1 kV/m |
b. |
2 kV/m |

c. |
1.4 kV/m |
d. |
0.7 kV/m |

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]

a. |
1 kV/m |
b. |
2 kV/m |

c. |
1.4 kV/m |
d. |
0.7 kV/m |

1 Answer

127 votes

Intensity of EM wave is given by

I = = ^{ }C

= = × 9 × 10^{−12 }× E^{2 }× 3 ×10^{8}

E = × 10^{3} kV/m

= 1.4 kV/m

127 votes

127