What is the wavelength of the light emitted when an electron in a hydrogen atom undergoes transition from the energy level n = 4 to energy level n = 2? What is the colour corresponding to their wavelengths? (Given RH=109677 cm−1)
486 nm, Blue
According to Balmer equation,
Wave number (¯ν)=RH[1n21−1n22]cm−1
n1=2, n2=4, RH=109677 cm−1
Substituting all the values, we get
¯ν=109677[1(2)2−1(4)2]cm−1=109677×316cm−1
Or λ=1¯ν=16109677×3cm=486 nm
The wavelength corresponds to blue color.