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The wavelength of light from the spectra...

The wavelength of light from the spectral emission line of sodium is 589 nm. Find the kinetic energy at which
an electron moves

Text Solution

Verified by Experts

Given `:` `lambda = 589 nm = 5.89 xx 10^(-7) m`
The de Broglie wavelength `lambda - ( h )/( p ) = ( h )/( sqrt( 2mE_(k))) `
`rArr lambda^(2) = ( h^(2))/(2mE_(k))`
Kinetic energy `E_(k )=( h^(2))/( 2mlambda^(2))`
For electron `E_(k) = ( h^(2))/( 2m lambda^(2))`
`E_(k) = ( ( 6.63 xx 10^(-34)))/(2.91xx 10^(-31) xx ( 5.89 xx 10^(-7))^(2))`
`= 6.96 xx 10^(-25) J`
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