The sun gives light at the rate of 1500 W/m2 of area perpendicular to the direction of light. Assume the wavelength of light as 5000 Å. Calculate the number of photons/s arriving at 1 m2 area at that part of the earth.
Correct answer: C. 3. 770 x 10^21
- A. 4.770 x 10^21
- B. 3.770 x 10^11
- C. 3. 770 x 10^21
- D. 3.770 x 10^22
Explanation
The explanation is given below:l= 1500 W/m^2λ=5000ÅE= hfE= hc/λAs c is the speed of light = 3×10^8 h is plank's constant =6.626 × 10^-34 m^2 kg / sNumber of photons received n = I/E n = Iλ/hc n = (1500)(5000Å)/(6.626 × 10^-34 )( 3×10^8) n = 3.77×10^21
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About Dawn of Modern Physics
Classical physics cannot explain blackbody radiation and related observations, leading to Planck’s quantum theory, in which energy is emitted or absorbed in discrete packets. Photons provide the particle model of light, with energy and momentum linked to frequency and wavelength, including the photoelectric effect and its threshold frequency.
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