A 25 watt bulb emits monochromatic yellow light of wavelength of ` 0. 57 mu` m. Calculate the rate of emission of quanta per second .

Explanation

Power of bulb, P = 25 Watt = `25 Js ^(-1)`
Energy of one photon, E = hν `=(hc)/lamda`
Substituting the values in the given expression of E:
`E = ((6.626xx10^(-34))(3xx10^(8)))/((0.57xx10^(-6))=34.87xx10^(-20J`
`E= 34.87xx10^(-20) J `
Rate of emission of quanta per second
`25/(34.87xx10^(-20))=7.169xx10^(19s^(-1)`