Number of photons emitted by a 100 ~W ( Js ⁻¹ ) yellow lamp in 1.0 s is ( of yellow light is 560 nm )

Step-by-step solution

As we know that, aligned & E = Nh = N hc & N = E hc ( i ) aligned E =100 ~W ( Js ⁻¹ ) 1 ~s =100 ~J Putting the value in eq. (i) we get aligned N & = 100 ~J 560 10⁻⁹ ~m 6.626 10⁻³⁴ Js 3 10^8 ~ms ⁻¹ & =2.82 10²⁰ aligned