A laser has a power of 21.7 W and a beam radius of 0.510 mm. (a) Find the intens

Question

A laser has a power of 21.7 W and a beam radius of 0.510 mm. (a) Find the intensity of the laser. W/m2 (b) Suppose you were floating in space and pointed the laser beam away from you. What would your acceleration be? Assume your total mass, including equipment, is 72.7 kg and that the force is directed through your center of mass. Hint: The change in momentum is the same as in the nonreflective case. m/s2 (c) Calculate your acceleration if it were due to the gravity of a space station with mass 1.20 106 kg and center of mass 113.8 m away. m/s2 (d) Calculate the peak electric and magnetic fields of the laser. Emax = N/C Bmax = T If you were planning to use your laser welding torch as a thruster to get you back to the station, don't bother because the force of gravity is stronger. Better yet, get somebody to toss you a line.

Explanation / Answer

intensity = 21.7/(*(0.51*0.001)2)

from the relation E=m*c2 , c = speed of light, m = mass of photon

P = power = (dm/dt)*c2

we find (dm/dt) (mass of photon released per unit time)

Thus force on body (F)= c*dm/dt

thus acceleration = F/M , M = 72.7kg

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