Question

please solve 18 19 &20 thank you!

18. What is the maximum kinetic energy of an electron ejected from a sodium surface whose won function is Wo = 2.28 eV when illuminated by light of wavelength 410 nm 19. Calculate the energy of red light photon with a wavelength of 750 nm in eV 20. Two stars star A and star B are the same size. The temperature of star A is 8000 K and the temperature of star B is 7000 K. How do their total luminosities compare. A is 1.7 x B

Answer 1

] 8. from the concept of photo electric affect the maximm kit of the electm, trwa - wo - As, Given, R = 4100m 2910x10 m. koho - 6.63 xro? Bxr er T 410x10 1.68109 – 3.03 ev { rev=1.68103 -19 Wo = 2.28 ev. then from (in murr = (3.03- 2. 28) er = 0.75 en - 0.75 er La we have, enrgy of a Phorten, with wavelogh L. va el AS. = 6.63 x 18 34 ... (a 3x10ress. - 750x109 from an 6.63 x 3 x 750 x 109 & 2.652 810 Leer -344 6.63 xlo X3 X 10 E- 7 & 1.6 1.6x109 La 2 a = 1.66 er - This is the red light Photon. energy of