A light wave with wavelength 590nm shines upon a metal and causes it to emit an electron with a speed of 5x10^5 m/s. What is the work function of the metal?
The first step for this question is to find out how much energy is absorbed by the electron above its work function. This is found with the kinetic energy equation: K.E.=1/2mv^2 The mass of an electron is 9.1x10^-31. Using this in the above equation finds the kinetic energy to be: K.E=0.59.1x10^-31(5x10^5)^2= 1.14x10^-19 J The kinetic energy is the energy above the work function. The energy provided from the photon of light is calculated with: E=(h*c)/L where E is the energy, h is the planck constant, c is the speed of light, and L is the wavelength.Inputting the correct values into the above equation gives: E=6.63 x 10^-34 x 3.0 x 10^8 / 5.9 x 10^-7= 3.37x10-19 J Finally, the work function can be found by subtracting the kinetic energy from the energy provided by the photon to give: W.F.= (3.37-1.14)x10^-19= 2.23x10^-19 J
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