CBSE Class 12 Physics Modern Physics Exam Notes

Advanced Study Material for Class 12 Physics: Modern Physics

Access comprehensive study materials and useful resources for Modern Physics using the CBSE Class 12 Physics Modern Physics Exam Notes. Designed to align with the 2026-27 CBSE academic guidelines, these advanced resources help Class 12 Physics students reinforce core concepts beyond standard textbooks.

Practice Class 12 Physics Resources: Modern Physics

Navigate directly to the advanced Physics study materials using the digital viewer below. Each resource pack includes detailed conceptual summaries and solved practice questions, allowing students to instantly reinforce their learning.

CBSE Class 12 Physics Modern Physics Exam Notes. Please refer to the examination notes which you can use for preparing and revising for exams. These notes will help you to revise the concepts quickly and get good marks.

Bohr’s Model for atom
Bohr’s theory is a combination of classical and quantum approach. It removes the draw backs of Rutherford’s model according to which electron should loose energy while revolving around nucleus and finally should fall into nucleus. When electron goes from orbit to another it can orbit or radiate electromagnetic radiation. Postulates
(i) electron moves in circular path around nucleus under the influence of electrostatic attraction between electron and nucleus.
(ii) electron can move only in selected orbits in which electron can have angular momentum integer multiply of .h/2π
i.e., mvr = nh/2π
where h is plank’s constant and n is shell no.

class_12_physics_useful_0109

class_12_physics_useful_0110

Interpretation of hydrogen spectrum

The electron in the hydrogen atom resides in the first orbit. When energy is supplied, the electron moves to higher energy shells depending on the amount of energy absorbed. When this electron returns to any of the lower energy level, it emits energy. Lyman series is obtained when the electron returns to the lowest energy state while Balmer series is obtained
when the electron returns to second energy shell. Similarly, Pashcen, Brackett and Pfund series are obtained when electron returns to the third, fourth and fifth energy shell from higher energy shells respectively.

class_12_physics_useful_0111

 

Modern Physics MCQ Questions with Answers Class 12 Physics 

 

Q.- Light of two different frequencies whose photons have energies 1 eV and 2.5 eV successively illuminate a metal of work function 0.5 eV. The ratio of the maximum speeds of the emitted electrons will be
(a) 1 : 5
(b) 1 : 4
(c) 1 : 2
(d) 1 : 1
Ans-(b)
 
Q.-The work function of a metal in 4 eV. For the emission of photoelectrons of zero velocity from the metal surface, the wavelength of the incident radiation should be
(a) 1700 Å
(b) 2700 Å
(c) 3100 Å
(d) 5900 Å
Ans-(b)
 
Q.- Photons of frequency v fall on a metal surface for which the threshold frequency is v0. Then,
(a) All ejected electrons have the same kinetic energy h(v – v0)
(b) the ejected electrons have a distribution of kinetic energy from zero to h(v – v0)
(c) the most energetic electrons have kinetic energy hv
(d) the average kinetic energy of ejected electrons is hv0.
Ans-(b)
 
Q.- An electron makes transition inside a hydrogen atom. The orbital angular momentum of the electron may change by
(a) h
(b) h/π
(c) h/2π
(d)h/4π
Ans-(b, c)
 
Q.- An electron in the ground state of hydrogen has an angular momentum L1, and an electron in the first excited state of lithium has an angular momentum L2.
(a) L1 = L2
(b) L1 = 4L2
(c) L2 = 2L1
(d) L1 = 2L2
Ans-(c)
 
Q.- The ratio of the energies of the hydrogen atom in the first to the second excited state
(a) 4 : 1
(b) 1 : 4
(c) 4 : 9
(d) 9 : 4
Ans-(d)
 
Q.- A hydrogen atom emits a photon corresponding to an electron transition from n = 5 to n = 1. The recoil speed of hydrogen atom is almost
(a) 10–4 ms–1
(b) 2 × 10–2 ms–1
(c) 4 ms–1
(d) 8 × 102 ms–1
Ans-(c)
 
Q.- In Bohr’s Model of hydrogen atom. The ratio between the period of revolution of an electron in orbit of n = 1 to the period of revolution of the electron in the orbit n = 2
(a) 1 : 2
(b) 2 : 1
(c) 1 : 4
(d) 1 : 8
Ans-(d)

Q.- The ratio of areas between the electron orbits for the first excited state to the ground state for the hydrogen atom is
(a) 2 : 1
(b) 4 : 1
(c) 8 : 1
(d) 16 : 1
Ans-(d)

Q.- The kinetic energy of an electron in the first orbit of H atom is 13.6 eV. The total energy of an electron in the second orbit of He+ is
(a) 13.6 eV
(b) 3.4 eV
(c) –13.6 eV
(d) –3.4 eV
Ans-(c)

Q.- The transition from the state n = 4 to n = 3 in a hydrogen like atom results in ultraviolet radiation. Infrared radiation will be obtained in the transition
(a) 2 → 1
(b) 3 → 2
(c) 4 → 2
(d) 5 → 4
Ans-(d)
 
Q.- Let v1 be the frequency of the series limit of the Lyman series, v2 be the frequency of the first line of the Lyman series, and v3 be the frequency of the series limit of the Balmer series.
(a) v1 – v2 = v3
(b) v2 – v1 = v3
(c) v3 =1/2 (v1 + v2)
(d) v1 + v2 = v3
Ans-(a)
 
Q.- The ratio of the wavelength of the first line of Lyman series to the first line of Balmer series is
(a) 1 : 4
(b) 5 : 27
(c) 27 : 20
(d) 20 : 27
Ans-(b)
 
Q.- The wavelength of the first line of Lymans series of hydrogen is 1216 Å. The wavelength of the second line of the same series will be
(a) 912 Å
(b) 1026 Å
(c) 3648 Å
(d) 6566 Å
Ans-(b)
 
Q.- The absorption transition between the first and the fourth energy states of hydrogen atom are 3. The emission transitions between these states will be
(a) 3
(b) 4
(c) 5
(d) 6
Ans-(d)
 
Q.- Which of the following transitions in the hydrogen atom emit the photon of highest frequency ?
(a) n = 2 to n = 6
(b) n = 6 to n = 2
(c) n = 1 to n = 2
(d) n = 2 to n = 1
Ans-(d)
 
Q.- The ratio of minimum to maximum wavelength in Balmer series is
(a) 5 : 9
(b) 5 : 36
(a) 1 : 4
(d) 3 : 4
Ans-(a)
 
Q.- The net force between two nucleons 1 fm apart is F1 if both are protons, F2 if both are neutrons, and F3 if one is a neutron and the other is a proton.
(a) F1 < F2 < F3
(b) F2 < F1 < F3
(c) F1 < F2 = F3
(d) F1 = F2 < F3
Ans-(c)

Q.- Mp denotes the mass of a proton and Mn denotes the mass of a neutron. A given nucleus of B.E. B contains Z protons and N neutrons. The mass M (N, Z) of the nucleus is given by (c is velocity of light)
(a) M (N, Z) = N Mn + XMp – B/c2
(b) M (N, Z) = N Mn + XMp + B/c2
(c) M (N, Z) = N Mn + XMp – Bc2
(d) M (N, Z) = N Mn + XMp + Bc2
Ans-(a)

Q.- If a star can convert all the He nuclei completely into oxygen nuclei, the energy released per oxygen nucleus is [Mass of He nucleus is 4.0026 amu and mass of Oxygen nucleus is 15.9994 amu]
(a) 7.6 MeV
(b) 56.12 MeV
(c) 10.24 MeV
(d) 23.9 MeV
Ans-(c)

Q.- The binding energy of deutron is 2.2 MeV and that of 2He4 is 28 MeV. If two deutrons are fused to form one 2He4, then the energy released is
(a) 19.2 MeV
(b) 23.6 MeV
(c) 25.8 MeV
(d) 30.2 MeV
Ans-(b)
 
Q.-The binding energy per nucleon for the parent nucleus is E1 and that for the daughter nuclei is E2. Then
(a) E1 > E2
(b) E2 > E1
(c) E1 > 2 E2
(b) E2 = 2 E1
Ans-(b)
 
Q.- Li nucleus has three protons and four neutrons. Mass of Li nucleus is 7.016005 amu. Mass of proton is 1.007277 amu. and mass of neutron is 1.008665 amu. Mass defect of lithium nucleus is amu is
(a) 0.04048 amu
(b) 0.4050 amu
(c) 0.04052 amu
(d) 0.04055 amu
Ans-(a)
 
Q.- An atom bomb weighing 1 kg explodes releasing 9 × 1013 joule of energy. What percentage of mass is converted into energy ?
(a) 1%
(b) 2%
(c) 0.1%
(d) 10%
Ans-(c)
 
Q.- Halflives of two radioactive substances A and B are respectively 20 minutes and 40 minutes. Initially the samples of A and B have equal number of nuclei. After 80 minutes, the ratio of remaining numbers of A and B nuclei is
(a) 1 : 16
(b) 4 : 1
(c) 1 : 4
(d) 1 : 1
Ans-(c)
 
Q.- The halflife period of a radioactive substance is 5 min. The amount of substance decayed in 20 min. will be
(a) 93.75%
(b) 75%
(c) 25%
(d) 6.25%
Ans-(a)
 
Q.- Rn decays into Po by emitting an α–particle with half life of 4 days. A sample contains 6.4 × 1010 atoms of Rn. After 12 days, the number of atoms of Rn left in the sample will be
(a) 3.2 × 1010
(b) 0.53 × 1010
(c) 2.1 × 1010
(d) 0.8 × 1010
Ans-(d)
 
Q.- The half life of radium is about 1600 years. Of 100 g of radium existing now, 25 g will remain unchanged after
(a) 2400 yrs
(b) 3200 yrs
(c) 4800 yrs
(d) 6400 yrs
Ans-(b)
 
Q.- C14 has half life 5700 years. At the end of 11400 years, the actual amount left is
(a) 0.5 g of original amount
(b) 0.25 of original amount
(c) 0.125 of original amount
(d) none of the above
Ans-(b)

Q.- The function of a moderator in a nuclear reactor is
(a) absorb the dangerous gamma radiation
(b) react with the nuclear fuel to release energy
(c) provide neutrons to the fission process
(d) slow down fast neutrons so as to have greater probability for nuclear fission to occur
Ans-(d)

 

Please click on below link to download pdf file for CBSE Class 12 Physics Modern Physics Exam Notes.

Free study material for Physics

Physics Class 12 Exam Resources: Modern Physics

Core Study Kit: Class 12 Physics Modern Physics

Explore essential learning tools for Class 12 Physics Modern Physics. This curated collection features in-depth notes and targeted practice questions built around the active 2026 curriculum to streamline your daily revision.

NCERT-Aligned Solutions for Modern Physics

Built using official NCERT guidelines for Class 12 Physics, these materials provide reliable academic support. Integrating past examination questions and step-by-step solutions helps students understand official CBSE grading criteria.

Next Steps in Your Exam Preparation

For peak performance in upcoming evaluations, integrate official Physics sample papers directly into your study schedule. Follow up your revision by attempting online MCQ tests for Modern Physics to refine calculation speed and precision.

FAQs

What is included in the advanced study material for Class 12 Physics Modern Physics?

Our advanced study package for Modern Physics includes detailed concepts, diagrams, Mind Maps, and explanation of complex topics to ensure Class 12 students learn as per syllabus for 2026 exams.

How do Mind Maps for Physics Modern Physics help in revision?

The Mind Maps provided for Modern Physics act as visual anchors which will help faster recall during high-pressure exams.

Are these Physics resources suitable for both classroom teaching and self-study?

Yes, teachers use our Class 12 Physics resources for lesson planning as they are in simple language and have lot of solved examples.

Is this advanced study material for Modern Physics free to download in PDF?

Yes, You can download the complete, mobile-friendly PDF of the Physics Modern Physics advanced resources for free.

Does this material cover rationalized content for the 2026-27 CBSE session?

Yes, our subject matter experts have updated the Modern Physics material to align with the rationalized NCERT textbooks and have removed deleted topics and added new competency-based questions.