Question

In the hydrogen atom, an electron makes a transition from $$n =2$$  to $$n=1.$$  The magnetic field produced by the circulating electron at the nucleus -

A. decreases 16 times
B. increases 4 times
C. decreases 4 times
D. increases 32 times  
Answer :   increases 32 times
Solution :
$$\eqalign{ & \because B = \frac{{{\mu _0}I}}{{2r}}\,\,{\text{and}}\,\,I = \frac{e}{T} \cr & B = \frac{{{\mu _0}e}}{{2rT}}\,\,\left[ {r \propto {n^2},T \propto {n^5}} \right]; \cr & B \propto \frac{1}{{{n^5}}} \cr} $$

Releted MCQ Question on
Modern Physics >> Atoms And Nuclei

Releted Question 1

If elements with principal quantum number $$n > 4$$  were not allowed in nature, the number of possible elements would be

A. 60
B. 32
C. 4
D. 64
Releted Question 2

Consider the spectral line resulting from the transition $$n = 2 \to n = 1$$    in the atoms and ions given below. The shortest wavelength is produced by

A. Hydrogen atom
B. Deuterium atom
C. Singly ionized Helium
D. Doubly ionised Lithium
Releted Question 3

An energy of $$24.6\,eV$$  is required to remove one of the electrons from a neutral helium atom. The energy in $$\left( {eV} \right)$$  required to remove both the electrons from a neutral helium atom is

A. 38.2
B. 49.2
C. 51.8
D. 79.0
Releted Question 4

As per Bohr model, the minimum energy (in $$eV$$ ) required to remove an electron from the ground state of doubly ionized $$Li$$ atom $$\left( {Z = 3} \right)$$  is

A. 1.51
B. 13.6
C. 40.8
D. 122.4

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