Question
Question: We wish to observe an object which is 2.5 Å in size. The minimum energy photon that can be used-...
We wish to observe an object which is 2.5 Å in size. The minimum energy photon that can be used-
A
5 KeV
B
8 KeV
C
10 KeV
D
12 KeV
Answer
5 KeV
Explanation
Solution
In order for scattering to occur, the wavelength of the waves must be of the same order of magnitude or smaller than the size of the object being observed. Hence the largest possible wavelength we can use in the present problem is λmax = 2.5 Å. Hence minimum energy is
Emin = hνmin = 
= 
= 4.96 × 103 eV
= 5 KeV