Question

how many photons of wavelength lamda is equals to 600 nm must strikes a totally reflecting screen per second at normal incidence. so as to exert a force of 1 N?​

Answer 1

Explanation:

I think its best to use the Impulse-Momentum theorem.

Net External force= dP/dt. or (Integration) Fdt = (Integration) dP

Use de Broglie concept which says

h(plank’s constant)/P(momentum)=Wavelength

In all,

(10N)*(1s)= n(no of photons)*(delta P(net))=(n)*2(h/wavelength)

The answer should probably be (5)*10^27.

h=[6.63*(10^(-34)] And of course don’t forget the collisions are elastic in nature