Calculate the energy in joule corresponding to light of wavelength `45 nm` :
(Planck' constant `h = 6.63 xx 10^-34 Js` , speed of light `c = 3 xx 10^8 ms^-1`)

Options

A. `6.67xx10^(15)`
B. `6.67xx10^(11)`
C. `4.42xx10^(-15)`
D. `4.42xx10^(-18)`

Answer

D

Explanation

(d) The wavelength of light is related ot its energy by the equation, `E=(hc)/(lambda).(E=hv)`
Given, `lambda=45 nm = 45xx10^(-9)m ` [`:' 1nm = 10^(-9)m`]
Hence, `E=(6.63xx10^(-34)Js xx 3xx 10^(8)ms^(-1))/(45xx10^(-9)m)`
`=4.42xx10^(-18) J`
Hence, the energy corresponds to light of wavelength 45 nm is `4.42xx10^(-18)J`.