I need help with thefollowing question: You are an engineer designing a switch t

Question

I need help with thefollowing question:

You are an engineer designing a switch that works by thephotoelectric effect. The metal you wish to use in yourdevice requires 6.7x10-19  J/atom to remove anelectron.  Will the switch work if the light falling onthe metal has a wavlength of 540nm or greater?  Why orwhy not? Correct me if I'm wrong but so far I've figured out that for awavelength of 540 nm, the energy per photon is 3.68 x10-19 J/photon and the energy per mole is 2.22 x105 J/mol. How do I proceed from here? Thanks! I need help with thefollowing question:

You are an engineer designing a switch that works by thephotoelectric effect. The metal you wish to use in yourdevice requires 6.7x10-19  J/atom to remove anelectron.  Will the switch work if the light falling onthe metal has a wavlength of 540nm or greater?  Why orwhy not? Correct me if I'm wrong but so far I've figured out that for awavelength of 540 nm, the energy per photon is 3.68 x10-19 J/photon and the energy per mole is 2.22 x105 J/mol. How do I proceed from here? Thanks!

Explanation / Answer

Energy required to remove an electron E = 6.7 * 10^ -19 J / atom wavelength correspond ing to energy E is ' = hc /E                                                                   = [ 6.625 * 10 ^ -34 * 3 * 10 ^ 8 ] / [ 6.7 *10 ^ -19]                                                                    = 2.9664 * 10^ -7 m                                                                    = 296.64* 10 ^ -9 m                                                                    = 296.64 nm This wavelength is less than 540 nm . So, the switch is not working. If the wavelength is less than or equal to 296.64 nmthen only the switch works

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