A 100-watt light bulb radiates energy at a rate of 100 J/s. (The watt, a unit of

Question

A 100-watt light bulb radiates energy at a rate of 100 J/s. (The watt, a unit of power or energy over time, is defined as 1 J/s.) If all of the light emitted has a wavelength of 525 nm , how many photons are emitted per second?
Enter your answer numerically in terms of photons per second. Be sure to include three significant figures.









Microwave ovens use microwave radiation to heat food. The microwaves are absorbed by the water molecules in the food, which is transferred to other components of the food. As the water becomes hotter, so does the food.








Suppose that the microwave radiation has a wavelength of 11.8 cm . How many photons are required to heat 291 mL of coffee from 24 oC to 59.2 oC? Assume that the coffee has the same density, 0.997 g/mL , and specific heat capacity, 4.184 J/(gK) , as water over this temperature range.
Enter your answer numerically and in terms of number of photons. A 100-watt light bulb radiates energy at a rate of 100 J/s. (The watt, a unit of power or energy over time, is defined as 1 J/s.) If all of the light emitted has a wavelength of 525 nm , how many photons are emitted per second?
Enter your answer numerically in terms of photons per second. Be sure to include three significant figures.









Microwave ovens use microwave radiation to heat food. The microwaves are absorbed by the water molecules in the food, which is transferred to other components of the food. As the water becomes hotter, so does the food.








Suppose that the microwave radiation has a wavelength of 11.8 cm . How many photons are required to heat 291 mL of coffee from 24 oC to 59.2 oC? Assume that the coffee has the same density, 0.997 g/mL , and specific heat capacity, 4.184 J/(gK) , as water over this temperature range.
Enter your answer numerically and in terms of number of photons. A 100-watt light bulb radiates energy at a rate of 100 J/s. (The watt, a unit of power or energy over time, is defined as 1 J/s.) If all of the light emitted has a wavelength of 525 nm , how many photons are emitted per second?
Enter your answer numerically in terms of photons per second. Be sure to include three significant figures.









Microwave ovens use microwave radiation to heat food. The microwaves are absorbed by the water molecules in the food, which is transferred to other components of the food. As the water becomes hotter, so does the food.








Suppose that the microwave radiation has a wavelength of 11.8 cm . How many photons are required to heat 291 mL of coffee from 24 oC to 59.2 oC? Assume that the coffee has the same density, 0.997 g/mL , and specific heat capacity, 4.184 J/(gK) , as water over this temperature range.
Enter your answer numerically and in terms of number of photons. Microwave ovens use microwave radiation to heat food. The microwaves are absorbed by the water molecules in the food, which is transferred to other components of the food. As the water becomes hotter, so does the food.








Suppose that the microwave radiation has a wavelength of 11.8 cm . How many photons are required to heat 291 mL of coffee from 24 oC to 59.2 oC? Assume that the coffee has the same density, 0.997 g/mL , and specific heat capacity, 4.184 J/(gK) , as water over this temperature range.
Enter your answer numerically and in terms of number of photons.

Explanation / Answer

E= hC/wave length

h= planck's constant = 6.627*10-34 J.s, C= speed of light= 3*108m/s, wave length= 525 nm= 525*10-9 m

E= 6.627*10-34* 3*108/ (525*10-9)=3.8*10-9 J/ photon

but energy from 100 watt bulb= 100J/s

no of photons/s = 100/ (3.8*10-9)= 2.6*1020 phonts/s

2. in heating water from 24 deg.c to 59.2 deg.c, energy required= mass of water* specific heat* temperature difference= volume of water* density* specific heat* temperature difference= 291*0.997*4.184*(59.2-24)=42723 joules

energy of single photon at 11.8cm= 11.8/100 m= 0.118m, E= 6.627*10-34* 3*108/0.118=1.7*10-24 J/photon

no of photons= 42723/(1.7*10-24)=2.5*1028 photons

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