Question

In astronomical observations, signals observed from the distant stars are
generally weak. If the photon detector receives a total of 3.15 × 10–18 J from the
radiations of 600 nm, calculate the number of photons received by the detector.

Answer 1

Answer:

Explanation:

The energy of 1 photon, E=hν=  

λ

hc

​  

==  

600×10  

−9

 

6.626×10  

−34

×3.0×10  

8

 

​  

=3.31×10  

−19

J.  

The number of photons is  

3.31×10  

−19

 

3.15×10  

−18

 

​  

=9.52=10.

Answer 2

Answer :

• No. of photons recieved = 10.

Step-by-step explanation :

Given that,

• Total energy recieved = 3.15 × 10⁻¹⁸ J.
• Wavelength of radiation, λ = 600 nm = 600 × 10⁻⁹ m.

Also,

• Speed of light, c = 3 × 10⁸ ms⁻¹.
• Planck's constant, h = 6.626 × 10⁻³⁴ Js.

$\hrulefill$

We know, energy of one photon = $\rm{\dfrac{hc}{\lambda}}$

Putting the given values, we get,

$:\implies\rm{\dfrac{(6.626\times{}10^{-34}\:Js)(3\times{}10^8\:ms^{-1})}{(600\times{}10^{-9}\:m)}=3.313\times{}10^{-19}\:J}$

Again, we know total energy recieved =

$\rm{3.15\times{}10^{-18}\:J}$

∴ No. of photons recieved =

$:\implies\rm{\dfrac{3.15\times{}10^{-18}\:J}{3.313\times{}10^{-19}\:J}}$

$:\implies\rm{9.53=}\:\bold{10.}$