8. 3/4 points | Previous Answers SerPSE9 40.P.038.W A helium-neon laser produces

Question

8. 3/4 points | Previous Answers SerPSE9 40.P.038.W A helium-neon laser produces a beam of diameter 1.75 mm, delivering 2.70 x 1018 photons/s. Each photon has a wavelength of 633 nm (a) Calculate the amplitude of the electric field inside the beam. 16.30 kV/m (b) Calculate the amplitude of the magnetic field inside the beam. 54.33HT (c) If the beam shines perpendicularly onto a perfectly reflecting surface, what force does it exert on the surface? 5.65 (d) If the beam is absorbed by a block of ice at 0°C for 1.40 h, what mass of ice is melted? 4.74 How much total energy falls on the ice during this time? g Need Help?Read ItWatch It

Explanation / Answer

Part D.

Energy is given by:

Energy = Power*time = P*dt

P = power = no.of photon*energy per photon

Energy per photon = E = hc/lambda = 6.626*10^-34*3*10^8/(633*10^-9) = 3.14*10^-19 J/photon

P = (2.70*10^18 photons/sec)*(3.14*10^-19 J/photon) = 0.8478 W

dt = 1.40 hr = 5040 sec

Energy required to melt the ice is given by

Q = m*Lf

Lf = latent heat of fusion of water = 3.34*10^5 J/kg

m = mass of ice melted = ?

So,

Q = E

m*Lf = P*dt

m = P*dt/Lf

m = 0.8478*5040/(3.34*10^5) = 0.0128 kg = 12.8 gm

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