Electrons are ejected from a photoelectric cell with a maximum kinetic energy of 1.20 eV. If the incident light has a wavelength of 410nm, what is the work funtion?
e*(Phi) = h*c/(lambda) - (max K.E.)
= photon energy - (max electron energy)
Solve for the work function phi, in electron volts
h is Planck's constant
yes that is what i did..and the answer i got is 2.93 x 10^-19 .. but i think its wrong :S
Your answer is in Joules. The work function is always given in electron volts (or just "volts"). Divide your number by e, the electron charge, to get phi, the work function.
oh okay thank u =)
To find the work function of the photoelectric cell, we can use the equation relating the kinetic energy of the ejected electrons to the energy of the incident photons.
The formula is given by:
K.E. (kinetic energy) = Energy of photon - Work Function
Here, we are given the maximum kinetic energy of the ejected electrons, which is 1.20 eV. To use this value in the equation, we need to convert it into joules since the other quantities are in SI units.
1 eV is equivalent to 1.6 x 10^-19 joules. Therefore, the kinetic energy can be written as:
K.E. = 1.20 eV * (1.6 x 10^-19 J/eV) = 1.92 x 10^-19 J
Next, we can use the equation relating the energy of a photon to its wavelength:
Energy of a photon = (Planck's constant * Speed of light) / Wavelength
Planck's constant (h) is approximately 6.63 x 10^-34 J∙s and the speed of light (c) is approximately 3.00 x 10^8 m/s.
Now, we can substitute the given wavelength of 410 nm into the equation to find the energy of the photon:
Energy of photon = (6.63 x 10^-34 J∙s * 3.00 x 10^8 m/s) / (410 x 10^-9 m)
Calculating this value gives us the energy of the photon.
Finally, we can substitute the known values into the original equation and solve for the work function:
1.92 x 10^-19 J = (Energy of photon) - Work Function
Rearranging the equation to solve for the work function gives:
Work Function = (Energy of photon) - 1.92 x 10^-19 J
After calculating the values, you will obtain the work function of the photoelectric cell.