Question

When sodium metal is illuminated with light of wavelength 420nm, the kinetic energy of the electrons emitted are found to be 1.04x10-19J. When it is illuminated with a 310 nm wavelength of light, the kinetic energy is 2.704x10-19J. Calculate the value of Planck's constant and find the work function of sodium

Answer 1

Photoelectric Effect when a radiation of frequency sé N is thrown on a metal, electrons are ejected with UUTUULIZIT kinetic energy, KE. Sodium (Na) Metal The equation for fhotoelectric effect iss- (A) the ho + KE h Planck's constant ho work function and to threshold frequency to efect B) le hace + Ke e lebon. "ooga - Because past speed of light (3x10 m 5-) Data provided e s warehythm of Ljut * = 420mm ₂= 3 lonm KE, z 1:04x10-197 | Kega 2-704x10-19 J Now, Noves e hc + KE, + KE - gli Nr 215 a hc + KE do Since the metal is Subtract 0 and @ he (+ -1.). (KEL – KF,) Suome, work functions he (sto 11 ) = (2-704-1-04) X16 "I cases. 12 same in both the

h / 420-310 I (420) (310) .. 1.664x10-19 J - 3x108 mst 1-664 X10-19 J x 420 x 310 x 10 mp 3x108 xhs-'xllo ha 656.52 x 10-36 Js hz 6.565 x 10-34 Js - Planck's constant Using (A), huz hro + KE he - $ + KE (let's call you te familien) &= heu ke $= 6-565x10 -34 J8 x 3x10 8 ml - 1.64x10-19 g 420x10-9 y 8 2 4.69x10-195 - 1-04 x 10-19 J $ - (4.69- 1.04) x10-19 J 1 $ = 3.65X10-19 ] → Work function for sodium metal