Q. 204.3( 3 Votes )

# Consider a metal exposed to light of wavelength 600 nm. The maximum energy of the electron doubles when light of wavelength 400 nm is used. Find the work function in eV.

Answer :

The maximum kinetic energy (K_{max}) for an electron is a function of its work function (φ) as well as the energy of the incident radiation.

Let K_{max} of the electron be K_{1} when incident light has wavelength 600 nm and K_{2} when incident light has wavelength 400 nm. Note 1 nm = 10^{-9} m

According to the question, K_{2} is two times K_{1}

To convert joule to eV, we can simply divide the value by 1.6 10^{-19}. Thus, work function in electron volts can be determined by

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