Question

please.. Solve the full answer.. URGENT

Answer 1

Energy (E) of a photon = hc/λ

Where,λ = wavelength of light = 4000 pm = 4000 ×10–12 m = 4x 10-9 m

c = velocity of light in vacuum = 3 × 108 m/s

h = Planck’s constant = 6.626 × 10–34 Js

thefore the energy of photon (E)

= 6.626 × 10–34 Js X 3 × 108 m/s / 4x 10-9 m = 4.965 x 10-16 J

Now 4.965 x 10-16 J is the energy of = 1 photon

Therefore 1 J will be the energy of = 1/4.965 x 10-16 J = 2.014 x 1015photons

Answer 2

Energy possesed by a Photon E = h v
where
h = Plank's constant = 6.36 × 10^ -34 J / s
v = frequency of photon
We know that velocity of light = wavelength × frequncy
=> frequency = velocity of light / wavelength
=> v = c / l , where
c = 3 × 10^8 m/s and l = 4000
so, v = 3 × 10 ^8 / 4000 = 3/4 × 10^5 --- (i)

Let there be n photons , then
Energy possesed by n photons
= n × hv
It is given that Eneregy possessed by n photons is 1J...
So we must have ,
E = n × hv
=> n = E / hv
= 1 / (6.36 x 10^ -34 ) × (3/4 x 10^5)
= ( 4 / 3 ) × 1 / 6.36 × 10^ -29
= ( 4 × 10 ^29) / 6.36
= ( 4 / 6.36 ) × 10 ^ 29
= 0.62 × 10^29
= 6.2 × 10^28