It takes #7.21 xx 10^-19\ "J"# of energy to remove an electron from an Fe atom. What is the wavelength of light that can do this?

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Answer 1 · 2018-03-31T01:02:30

#"0.578 nm"#

de-Broglie wavelength is given as

#λ = "h"/sqrt("2mK")#

where

#"h ="# Planck’s constant

#"m ="# Mass of electron

#"K ="# Kinetic energy of electron

#λ = (6.626 × 10^-34\ "J s")/sqrt(2 × 9.1 × 10^-31\ "kg" × 7.21 × 10^-19\ "J")#

#λ = 0.578 × 10^-9\ "m"#

#λ = 0.578 × cancel(10^-9\ "m") × "1 nm"/cancel(10^-9\ "m") = color(blue)"0.578 nm"#