Question

If a source of power 4 KW produces ${10^{20}}$photon/second then the radiation belongs to apart from the spectrum called
(A). y- rays
(B). X-rays
(C). ultraviolet rays
(D).microwaves

Answer 1

From the given data in the question first of all find the frequency of the radiation by the appropriate formula and calculation then select the appropriate range of the spectrum from the calculated frequency.

Complete step by step answer:
Given that
Power of the source is 4 kW
No of photon produced is $= {10^{20}}$per second
The Planck’s constant is $h = 6.023 \times {10^{ - 34}}{\rm{J}} \cdot {\rm{sec}}$
The power of a source is given by the following expression:
$P = N\left( {h\nu } \right)$
Now substitute all the given values in above equation we get
$4 \times {10^3} = \left( {{{10}^{20}}} \right)\left( {6.023 \times {{10}^{ - 34}}} \right)\left( \nu \right)$
Now solve the above expression, we get the value of frequency as
$\nu = 6.64 \times {10^{16}}{\rm{Hz}}$
Now, from the frequency chart see in which reason this frequency lies. When we see this, we find that this frequency lies in the bond of X-rays.
Therefore, the spectrum that belongs to the emitted radiation of the power source belongs to the X-rays.

So, the correct answer is “Option B”.

Additional Information:
In physics radiation energy is the energy that reflects in a straight line like a Ray. It is the energy of electromagnetic waves. Its SI unit is Joule. The value of radiant energy can be calculated from the flux method

Note:
The emitted power of a source mainly depends upon the number of photons produced per second so be careful to multiply the total number of photons produced per second while doing calculations and carefully watch the range of obtained frequency to find the correct type of rays produced.