Match the temperature of a black body given in List-I with an appropriate statement in List-II, and choose the correct option. [Given: Wien’s constant as 2.9 × 10−3 m-K and hc/e = 1.24 × 10−6 V-m
| List-I | List-II |
|---|---|
| (P) | (1) |
| (Q) | (2) |
| (R) | (3) |
| (S) | (4) |
| (5) |
Correct Answer :
P → 3, Q → 4, R → 2, S → 1
Solution :
The correct option is P → 3, Q → 4, R → 2, S → 1.
To match each black body temperature in List-I with the corresponding statement in List-II, let us analyze the physical laws involved step-by-step:
1. Wien's Displacement Law:
The peak wavelength of radiation emitted by a black body at absolute temperature is given by:
where is Wien's constant.
2. Stefan-Boltzmann Law:
The total power emitted per unit area by a black body is proportional to the fourth power of its absolute temperature:
3. Single Slit Diffraction Central Maximum:
The angular width of the central maximum in single slit diffraction is given by:
Thus, a larger wavelength results in a wider central maximum.
Now, let us evaluate each item in List-I:
Analysis of (P) :
The peak wavelength is calculated as:
Among all given temperatures, produces the longest peak wavelength (). Since diffraction width is directly proportional to wavelength, this peak wavelength results in the widest central maximum.
P matches with (3).
Analysis of (Q) :
Using Stefan-Boltzmann law, compare the power per unit area emitted at to that at :
The power emitted per unit area is indeed of that emitted at .
Q matches with (4).
Analysis of (R) :
The peak wavelength is calculated as:
A wavelength of lies in the yellow region of the visible light spectrum ( to ). Therefore, the radiation at peak wavelength is visible to the human eye.
R matches with (2).
Analysis of (S) :
The peak wavelength is calculated as:
The energy of a photon corresponding to this peak wavelength is:
Since photon energy (work function), this radiation can cause the photoelectric emission of electrons from the metal surface.
S matches with (1).
Hence, the correct matching is: P → 3, Q → 4, R → 2, S → 1.
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