Neon gas is generally used in the sign boards. If it emits with wavelength of 616 nm, calculate
(i) the frequency of emission
(ii) energy of quantum and
(iii) distance travelled by this radiation in 30 s.

Explanation

`lambda_("neon") = 616 nm = 616 xx 10^(-9)m`
(i) `v_("Neon") = (c)/(lambda) = (3 xx 10^(8) m.s^(-1))/(616 xx 10^(-9) m) = 0.00487 xx 10^(17) s^(-1)`
`= 4.87 xx 10^(14) s^(-1)` (or Hertz)
(ii) `E = h V = 6.625 xx 10^(-34) J.s xx 4.87 xx 10^(14)s^(-1)`
`= 32.26 xx 10^(-20) J`
(iii) distance travelled = Velocity `xx` time `= 3 xx 10^(8) m.s^(-1) xx 30s = 90 xx 10^(8)m = 90 xx 10^(5)` km.