Answer
Verified
439.5k+ views
Hint:We are given with a point source that is emitting light in all possible directions. The power of the source is P and the wavelength of the light being emitted is λ. We know point source produces spherical wavefront that goes out.
Complete step by step answer:
We need to find first of all energy density because we have to take into account some specific area. We can write energy in terms of power as \[E=Pt\]. Now the time taken by the light to move a distance from r to (r+x) that is distance x is \[t=\dfrac{x}{c}\], where c is the speed of light. So, E= \[\dfrac{Px}{c}\]
Since light energy is carried by photons and if the energy of one photon is given as \[\dfrac{hc}{\lambda }\]where h is the Planck’s constant and c is the speed of light. So, we can write the energy as \[E=N(\dfrac{hc}{\lambda })=\dfrac{Px}{c}\]
\[N=\dfrac{Px\lambda }{h{{c}^{2}}}\]
So, the correct option is (B).
Note:The point source of light sends away light in all directions and the wavefront is spherical. Also, from Planck’s quantum theory light travels in the form of photons and phonons are the smallest quanta of energy. Photon's rest mass is zero and thus, the photon can be freely created and destroyed. It does not violate the law of conservation of energy.
Complete step by step answer:
We need to find first of all energy density because we have to take into account some specific area. We can write energy in terms of power as \[E=Pt\]. Now the time taken by the light to move a distance from r to (r+x) that is distance x is \[t=\dfrac{x}{c}\], where c is the speed of light. So, E= \[\dfrac{Px}{c}\]
Since light energy is carried by photons and if the energy of one photon is given as \[\dfrac{hc}{\lambda }\]where h is the Planck’s constant and c is the speed of light. So, we can write the energy as \[E=N(\dfrac{hc}{\lambda })=\dfrac{Px}{c}\]
\[N=\dfrac{Px\lambda }{h{{c}^{2}}}\]
So, the correct option is (B).
Note:The point source of light sends away light in all directions and the wavefront is spherical. Also, from Planck’s quantum theory light travels in the form of photons and phonons are the smallest quanta of energy. Photon's rest mass is zero and thus, the photon can be freely created and destroyed. It does not violate the law of conservation of energy.
Recently Updated Pages
How many sigma and pi bonds are present in HCequiv class 11 chemistry CBSE
Mark and label the given geoinformation on the outline class 11 social science CBSE
When people say No pun intended what does that mea class 8 english CBSE
Name the states which share their boundary with Indias class 9 social science CBSE
Give an account of the Northern Plains of India class 9 social science CBSE
Change the following sentences into negative and interrogative class 10 english CBSE
Trending doubts
Which are the Top 10 Largest Countries of the World?
Difference between Prokaryotic cell and Eukaryotic class 11 biology CBSE
Fill the blanks with the suitable prepositions 1 The class 9 english CBSE
Difference Between Plant Cell and Animal Cell
Give 10 examples for herbs , shrubs , climbers , creepers
Differentiate between homogeneous and heterogeneous class 12 chemistry CBSE
The Equation xxx + 2 is Satisfied when x is Equal to Class 10 Maths
How do you graph the function fx 4x class 9 maths CBSE
Write a letter to the principal requesting him to grant class 10 english CBSE