[Given: Wien's constant as and ]
| List - I | List - II |
|---|---|
| (P) | (1) The radiation at peak wavelength can lead to emission of photoelectrons from a metal of work function . |
| (Q) | (2) The radiation at peak wavelength is visible to human eye. |
| (R) | (3) The radiation at peak emission wavelength will result in the widest central maximum of a single slit diffraction. |
| (S) | (4) The power emitted per unit area is of that emitted by a blackbody at temperature . |
| (5) The radiation at peak emission wavelength can be used to image human bones. |
- A
- B
- C
- D
View written solutionFree
Correct answer: C
- Use Wien’s displacement law
For a black body,
So,
Let us compute for each temperature.
-
(P)
This is in the infrared region.
-
(Q)
This is also infrared.
-
(R)
This lies in the visible region.
-
(S)
This is ultraviolet.
- Match with statement (3): widest central maximum in single slit diffraction
For a single slit,
So the largest wavelength gives the widest central maximum.
Among all temperatures, the largest is for 2000 K.
Hence,
- Match with statement (4): power emitted per unit area is of that at
Using Stefan–Boltzmann law,
We need
Taking fourth root,
So,
Thus,
- Match with statement (2): radiation at peak wavelength is visible to human eye
Visible range is approximately
From above,
- : not visible
- : not visible
- : visible
- : not visible
Hence,
- Match with statement (1): peak radiation can emit photoelectrons from a metal of work function
For photoelectric emission,
or
Given,
Thus photon energy in eV is
For (S), :
Since , photoemission is possible.
Hence,
- Check statement (5): can be used to image human bones
Imaging bones requires X-rays, which have much smaller wavelengths than UV/visible/IR. None of the peak wavelengths except certainly not correspond to X-rays. So statement (5) is not used.
- Final matching
Thus the correct matching is:
This corresponds to Option C.
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