In: Chemistry
Find the velocity of an electron emitted by a metal whose threshold frequency is 2.46×1014 s−1 when it is exposed to visible light of wavelength 4.79×10−7 m .
E = hc/
= 6.625*10^-34 * 3*10^8/4.79*10^-7
= 4.15*10^-19 J
threshold frequency is 2.46×1014 s−1
E = hv0
= 6.625*10^-34*2.46*10^14 = 1.63*10^-19 J
The emitted electron energy ( Kinetic energy) = energy of photon - threshold energy
= 4.15*10^-19- 1.63*10^-19 = (4.15-1.63)*10^-19 = 2.52*10^-19 J
1/2 mv^2 = 2.52*10^-19
mv^2 = 2.52*10^-19 *2 = 5.04*10^-19
V^2 = 5.04*10^-19/9.1*10^-31
V^2 = 5.54*10^11
V = 7.44*10^5 m/sec >>>>answer
velocity of electron = 7.44*10^5 m/sec