Question

What is the longest wavelength of light that will

emitelectrons from a metal whose work function is 3.10 eV?

Answer 1

The longest wavelength equals
`0.4* 10^(-6)m`

Step-by-step explanation:

According to Einstein's photoelectric equation we have

`E_(incident)\geq \phi`

where

`E_(incident)` is the energy of the incident light

`\phi` is the work function of the metal

The incident energy of the light with wavelength
`\lambda` is given by

`E_(incident)=h\cdot (c)/(\lambda)`

Thus the photoelectric equation reduces to

`h\cdot (c)/(\lambda)\geq \phi\\\\h\cdot c\geq \lambda * \phi\\\\\therefore \lambda\leq (h\cdot c)/(\phi)`

Thus applying values we get

`\lambda\leq (6.62* 10^(-34)* 3* 10^(8))/(3.10* 1.602* 10^(-19))\\\\\therefore \lambda\leq 0.4* 10^(-6)m`

Hence The longest wavelength equals
`0.4* 10^(-6)m`