Neon gas is generally used in the sign boards. If it emits strongly at 616 nm, calculate (1) the frequency of emission, (2) distance travelled by this radiation in 30s (3) energy of quantum and (4) number of quanta present if it produces 2 J of energy.

Explanation

`lamda=616n m=616xx10^(-9)m,c=3xx10^(8)m*s^-1`
(1) Radiation frequency,
`v=(c)/(lamda)=(3xx10^(8))/(616xx10^(-9))=4.87xx10^(14)s^(-1)`
(2) Distance (s) travelled by the radiation in 30s=`cxxt=3xx10^(8)m*s^(-1)xx30s=9xx10^(9)m`
(3) Energy of quantum
`E=hv=6.626xx10^(-34)xx4.87xx10^(14)=3.23xx10^(-19)J`
(4) Number of quanta`=("total energy")/("enerrgy of each quantum")`
`=(2J)/(3.23xx10^(-19)J)=6.19xx10^(18)`.