6.101 Laser welding is a technique in which a tightly focused laser beam is used to deposit enough energy to weld metal parts together. Because the entire process can be automated, it is commonly used in many large-scale industries, including the manufacture of automobiles. In order to achieve the desired weld quality, the steel parts being joined must absorb energy at a rate of about 10 4 W/mm 2 . (Recall that 1 W = 1 J/s.) A particular laser welding system employs a Nd:YAG laser operating at a wavelength of 1.06 μ m ; at this wavelength steel will absorb about 80% of the incident photons. If the laser beam is focused to illuminate a circular spot with a diameter of 0.02 inch, what is the minimum power (in watts) that the laser must emit to reach the 10 4 W/mm 2 threshold? How many photons per second does this correspond to? (For simplicity, assume that the energy from the laser does not penetrate into the metal to any significant depth.)
6.101 Laser welding is a technique in which a tightly focused laser beam is used to deposit enough energy to weld metal parts together. Because the entire process can be automated, it is commonly used in many large-scale industries, including the manufacture of automobiles. In order to achieve the desired weld quality, the steel parts being joined must absorb energy at a rate of about 10 4 W/mm 2 . (Recall that 1 W = 1 J/s.) A particular laser welding system employs a Nd:YAG laser operating at a wavelength of 1.06 μ m ; at this wavelength steel will absorb about 80% of the incident photons. If the laser beam is focused to illuminate a circular spot with a diameter of 0.02 inch, what is the minimum power (in watts) that the laser must emit to reach the 10 4 W/mm 2 threshold? How many photons per second does this correspond to? (For simplicity, assume that the energy from the laser does not penetrate into the metal to any significant depth.)
Solution Summary: The author describes laser beam welding as a technique used to join metal or thermoplastics through the use of lasers.
6.101 Laser welding is a technique in which a tightly focused laser beam is used to deposit enough energy to weld metal parts together. Because the entire process can be automated, it is commonly used in many large-scale industries, including the manufacture of automobiles. In order to achieve the desired weld quality, the steel parts being joined must absorb energy at a rate of about 104 W/mm2. (Recall that 1 W = 1 J/s.) A particular laser welding system employs a Nd:YAG laser operating at a wavelength of
1.06
μ
m
; at this wavelength steel will absorb about 80% of the incident photons. If the laser beam is focused to illuminate a circular spot with a diameter of 0.02 inch, what is the minimum power (in watts) that the laser must emit to reach the 104 W/mm2 threshold? How many photons per second does this correspond to? (For simplicity, assume that the energy from the laser does not penetrate into the metal to any significant depth.)
Equal masses of lead, copper, iron, and aluminum absorb 100 J of heat. Which metal will undergo the largest increase in temperature?
a) lead (specific heat: 0.160 J/g°C)
b) copper (0.385 J/g°C)
c) iron (0.473 J/g°C)
d) aluminum (specific heat: 0.900 J/g°C)
Which one of the following is associated with the emission of light from an atom?
a) an electron being removed from an atom to form a positively charged ion
b) an electron dropping from a higher energy state to a lower energy state
c) an electron rising from a lower energy state to a higher energy state
d) an electron entering an orbital that already contains another electron
A certain microwave oven delivers 750. watts (J/s) of power to a coffee cup containing 100.0 g water at 22.0°C. If the wavelength of microwaves in the oven is 9.75 cm, how long does it take, and how many photons must be absorbed, to make the water boil? The specific heat capacity of water is 4.18 J/°C*g, and assume only the water absorbs the energy of the microwaves. The speed of light is 3.0*108 and the Planck‘s constant is 6,63 * 10-34 J/s.
Microwave ovens use microwave radiation to heat food. The energy of the microwaves is absorbed by water molecules in the food and then transferred to the rest of the food. a. Suppose the microwave radiation has a wavelength of 11.2 cm. How many photons are required to heat 2.00 102 mL of coffee from 23 to 60 oC? b. If the power of the microwave is 9.00 102 W (1 Watt = 1 Joule/second), how long would you have to heat the coffee?
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Author:Steven D. Gammon, Ebbing, Darrell Ebbing, Steven D., Darrell; Gammon, Darrell Ebbing; Steven D. Gammon, Darrell D.; Gammon, Ebbing; Steven D. Gammon; Darrell
Author:Steven D. Gammon, Ebbing, Darrell Ebbing, Steven D., Darrell; Gammon, Darrell Ebbing; Steven D. Gammon, Darrell D.; Gammon, Ebbing; Steven D. Gammon; Darrell