SELECT * FROM question_mgmt as q WHERE id=2831 AND status=1 SELECT id,question_no,question,chapter FROM question_mgmt as q WHERE courseId=3 AND subId=8 AND chapterId=126 and ex_no='1' AND status=1 ORDER BY CAST(question_no AS UNSIGNED) CBSE Free NCERT Solution of 12th physics Atoms a 12 5 ev electron beam is used to bombard gaseous

Question:

A 12.5 eV electron beam is used to bombard gaseous hydrogen at room temperature. What series of wavelengths will be emitted?

Answer:

It is given that the energy of the electron beam used to bombard gaseous hydrogen at room temperature is 12.5 eV.

Also, the energy of the gaseous hydrogen in its ground state at room temperature is −13.6 eV.

When gaseous hydrogen is bombarded with an electron beam, the energy of the gaseous hydrogen becomes −13.6 + 12.5 eV i.e., −1.1 eV.

Orbital energy is related to orbit level (n) as:

E = -13.6/(n)2 eV

For n = 3, E = -13.6/(9)2 = -1.5 eV

This energy is approximately equal to the energy of gaseous hydrogen. It can be concluded that the electron has jumped from n = 1 to n = 3 level.

During its de-excitation, the electrons can jump from n = 3 to n = 1 directly, which forms a line of the Lyman series of the hydrogen spectrum.

We have the relation for wave number for Lyman series as:

1/λ = Ry (1/12 - 1/n2)

Where,

Ry = Rydberg constant = 1.097 × 107 m−1

λ= Wavelength of radiation emitted by the transition of the electron

For n = 3, we can obtain λ as:

1/λ = 1.097 x 107 (1/12 - 1/32)

= 1.097x107(1-1/9) = 1.097x107x8/9

λ = 9/(8 x 1.097 x 107) = 102.55 nm

If the electron jumps from n = 2 to n = 1, then the wavelength of the radiation is given as:

1/λ = 1.097 x 107 (1/12 - 1/22)

= 1.097x107(1-1/4) = 1.097x107x3/4

λ = 4/(1.097x107x3) = 121.54nm

If the transition takes place from n = 3 to n = 2, then the wavelength of the radiation is given as:

1/λ = 1.097 x 107 (1/22 - 1/32)

= 1.097x107(1/4-1/9) = 1.097x107x5/36

λ = 36/(5x1.097x107) = 656.33 nm

This radiation corresponds to the Balmer series of the hydrogen spectrum.

Hence, in Lyman series, two wavelengths i.e., 102.5 nm and 121.5 nm are emitted. And in the Balmer series, one wavelength i.e., 656.33 nm is emitted.


< Previous Question

Next Question >

SELECT ex_no,question,question_no,id,chapter FROM question_mgmt as q WHERE courseId='3' AND subId='8' AND ex_no!=0 AND status=1 and id!=2831 ORDER BY views desc, last_viewed_on desc limit 0,10

  • Popular questions of class 12 Physics

SELECT ex_no,question,question_no,id,chapter FROM question_mgmt as q WHERE courseId='3' AND subId='8' AND ex_no!=0 AND status=1 and id!=2831 ORDER BY last_viewed_on desc limit 0,10

  • Recently Viewed Questions of Class 12 Physics

Comments

  • Answered by Ekta Mehta
  • 4 months ago

Taking Screenshots on your Samsung Galaxy M31s is very easy and quick.

  • Answered by Ekta Mehta
  • 4 months ago

Taking Screenshots on your Samsung Galaxy M31s is very easy and quick.

  • Answered by Ekta Mehta
  • 4 months ago

Taking Screenshots on your Samsung Galaxy M31s is very easy and quick.

Comment(s) on this Question


NCERT Solutions

Quick Links

Resources

Support