the wavelength range of the visible spectrum extends from violet ( 400 nm) to red ( 750 nm). Express these wavelengths in frequencies (Hz) . (1nm =` 10 ^(-9)m`)

Explanation

Wavelength of violet light `lambda = 400 nm`
`" " = 400 xx 10^(-9) m`
Frequency , `v = c/(lambda)`
where c is speed of light = `3.0 xx 10^8 ms^(-1)`
`:. " " v = (3.0 xx 10^8 ms^(-1))/(400 xx 10^(-9) m)`
`= 7.5 xx 10^(14) Hz`
Wavelength of red light, `lambda = 750 nm`
`= 750 xx 10^(-9) m`
`:.` Frequency , `v = (c)/(lambda)`
`=(3.0 xx 10^8 ms^(-1))/(750 xx 10^(-9) m) = 4.0 xx 10^(14) Hz`
Thus, the range of visible spectrum in terms of frequency is from `4.0 xx 10^(14) Hz` to `7.5 xx 10^(14) Hz`.