A 36 W ultraviolet light source eits light of wavelength `2200Å`. This light illuminates a magnesium (Mg) surface placed 2m away. If the number of photons emitted from the surface per second canbe expressed in the form of `Yxx10^(19)s^(-1)`, then find the value of Y .(Take `h=6.6xx10^(-34)Js`)

Answer

`04.00`

Explanation

Energy of each photon,
`E=(hc)/(lamda)=(6.6xx10^(-4)xx3xx10^(9))/(2200xx10^(-10))=9xx10^(-19)`J
Number of phiotons emitted per second,
`N=P/E=36/(9xx10^(-19))=4xx10^(19)s^(-1)`
`:.Y=4`