Concept explainers
(a)
The amplitude of the electric field of the helium-neon laser.
(a)
Answer to Problem 38P
The amplitude of the electric field is
Explanation of Solution
The diameter of the beam of laser is
Write the formula for the energy of a single photon.
Here,
Write the formula for the power carried by the laser beam.
Here,
Write the formula for the average poynting vector.
Here,
Write the formula for the average poynting vector in terms of electric field.
Here,
Re-write the above equation to get an expression for
Conclusion:
Substitute
Substitute
Substitute
Substitute
The amplitude of the electric field is
(b)
The amplitude of the magnetic field of the helium-neon laser.
(b)
Answer to Problem 38P
The amplitude of the magnetic field is
Explanation of Solution
The diameter of the beam of laser is
Write the formula for the magnitude of the magnetic field.
Here,
Conclusion:
Substitute
The amplitude of the magnetic field is
(c)
The force exerted by the beam on a perfectly reflecting surface when it is incident perpendicularly.
(c)
Answer to Problem 38P
The force exerted on the perfectly reflecting surface is
Explanation of Solution
The diameter of the beam of laser is
Write the formula for the force exerted on the perfectly reflecting surface.
Here,
Conclusion:
Substitute
The force exerted on the perfectly reflecting surface is
(d)
The mass of the ice melted if the beam of laser is absorbed by an ice cube.
(d)
Answer to Problem 38P
The mass of the ice melted if the beam of laser is absorbed by an ice cube is
Explanation of Solution
The diameter of the beam of laser is
Write the formula for the mass of ice melted.
Here,
Conclusion:
Substitute
The mass of the ice melted if the beam of laser is absorbed by an ice cube is
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Chapter 40 Solutions
Physics for Scientists and Engineers With Modern Physics
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