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Lasers can be constructed to produce an extremely high-intensity electromagnetic

ID: 1553164 • Letter: L

Question

Lasers can be constructed to produce an extremely high-intensity electromagnetic wave for a very brief time. Such lasers arc called "pulsed lasers". They are used to ignite nuclear fusion, for example. Such a laser may produce an electromagnetic wave with a maximum electric field strength of 0.69 Times 10^11 V/m for a time of 0.85 ns. E_0 = 0.69 Times 10^11 V/m t = 0.85 ns (a) What is the maximum magnetic field strength in the wave B_0, in teslas? (b) What is the intensity of the beam I, in watts per square meter? (c) How much energy, in kilojoules, docs one pulse of the laser beam deliver to a 1.00 mm^2 area? E =

Explanation / Answer

(A) Bo = E0 / C

= 0.69 x 10^11 V/m / (3 x 10^8 m/s)

= 230 T

(B) I = Eo Bo / (2 u0)

= (0.69 x 10^11) (230) / (2 x 4pi x 10^-7)

= 6.31 x 10^18 W / m^2


(C) Energy = I A t

= (6.31 x 10^18) (1 x 10^-6) (0.85 x 10^-9)

= 5367.3 J