Frequency of violet light
`v = (c)/(lambda) = (3.00 xx 10^(8)ms^(-1))/(400 xx 10^(-9)m) = 7.50 xx 10^(14)Hz`
frequenct of red light
`v = (c)/(lambda) = (3.00 xx 10^(8)ms^(-1))/(750 xx 10^(-9)m) = 4.00 xx 10^(14)Hz`
The range of visible spectrum is from
`4.0 xx 10^(14)` to `7.5 xx 10^(14)Hz` in terms of frequency