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# NCERT Exemplar Class 12 Physics Chapter 11 Solutions: Dual Nature of Radiation and Matter

NCERT Exemplar Class 12 Physics Solutions Chapter 11 – Dual Nature of Radiation and Matter will help you to revise the complete syllabus to score high in CBSE Board exams. This chapter of NCERT Exemplar Class 12 Physics Solutions will explain major terminologies based on the dual nature of Radiation and Matter alongside helping you with the concepts of matter that propagates through Radiation.

NCERT Exemplar solution will also help you to understand the basic principle of a microscope in the subject of matter that exists as both a wave and a particle. Some major terminologies covered in NCERT Exemplar solution are: Einstein’s Photoelectric Emission, Emission of Electrons, Nature of Matter- Wave and Particle, Study of Photoelectric effect through experimentation, Davisson and Germer Experiment

NCERT Exemplar Class 12 Physics Solutions for Chapter – ‘Dual Nature of Radiation and Matter’ have a total of 29 questions that is divided into 5 sections touching all the topics based on Dual Nature of Radiation and Matter and related numerical. The questions are of various kinds which help you get a complete revision with the help of short and long type questions, objective type questions, and MCQs kind of questions which are important from the exam point of view. Instasolv has created Solutions to various NCERT Exemplar Solutions in unique and smooth steps that you can learn easily.

## Important Topics for NCERT Exemplar Class 12 Physics Solutions Chapter 11- Dual Nature of Radiation and Matter

• Electric Discharge:  It is the phenomenon of passing an electric current through a gas.
• Discharge Tube: A hard glass tube alongside the fundamental arrangement, which is utilized to contemplate the passage of electric discharge through gases at very low pressure, is known as a discharge tube.
• Cathode Rays: Cathode beams are the surge of negatively charged particles, electrons that are taken shots out at a higher speed from the cathode of a discharge tube under a pressure below 0.01 mm of Hg.
• Work Function:  It is the minimal amount of energy required by an electron to simply escape from the metal surface. It is measured by:

• Thermionic Emission: Here electrons are produced from the metal surface with the assistance of thermal energy.
• Field or Cold Cathode Emission: It is the emission of electrons from a metal surface when subjecting under the highest electric field.
• Photoelectric Emission: It is the emission of electrons that emerges from the surface of a metal with the assistance of thermal energy under suitable electromagnetic radiations.
• Secondary Emission: Electrons are shot out from a metal surface by striking over its high-speed electrons.
• Forces Experienced by an Electron in Electric and Magnetic Fields:-
1. Electric field: when a force FE accomplished by an electron e within an electric field of strength (intensity) E is given by, FEeE
2. Magnetic field: when a  force accomplished  by an electron e within a magnetic field of strength B Weber/m2 is given by, FB=Bev
where v = velocity because of which the electron moves within the electric field and the magnetic field, that are perpendicular to the direction of motion.
3. If the magnetic field is parallel to the direction of motion of the electron, then, FB 0.
• Photoelectric Effect:  when electrons are emitted from the surface of substances (i.e. metals) when subjected to electromagnetic radiations of defined frequency, it is called photoelectric effect and the electrons which are emitted are called photoelectrons.
• Cut Off or Stopping Potential: It is the retarding potential value at which the photoelectric current becomes null is known as cut off or stopping potential for that given frequency of the incident radiation.

• Threshold Frequency: The lowest value frequency of incident radiation below which the photoelectric emission ultimately stops is called threshold frequency.
• Laws of Photoelectric Effect:
1. Under a fixed frequency of given radiation, the photoelectrons are emitted that is proportional to incident radiation intensity.
2. For every metal, there is a certain minimal amount of frequency below which photoelectrons are not emitted, hence it is known as the called threshold frequency.
3. For the frequency of recurrence higher than the limit frequency, the kinetic energy of the photoelectrons is straightforwardly corresponding to the frequency of incident radiation and is independent of the intensity of incident radiation.
• Einstein’s Theory of Photoelectric Effect:-
1. Einstein mentioned Planck’s quantum theory to explain the photoelectric effect.
2. According to this theory, whenever radiation of frequency “v” incident over a metal surface, it gets absorbed as discrete packets of energy called quanta or photons.
3. Einstein’s photoelectric equation =

here, w0= work function of the metal.

• Photocell:
1. A photocell is an arrangement that involves the conversion of light energy into electric energy. Based on the principle of the photoelectric effect.
2. Mainly used in cinematography for the reproduction of sound.
• Dual Nature of Radiation:  we all know that Light behaves as dual nature. It displays wave in diffraction, interference, polarization, etc
• Davison and Germer Experiment: This experiment confirms the existence of de Broglie waves associated with electrons.
• De Broglie Wavelength of an Electron: it is the wavelength of light associated with one electron beam accelerated through a potential.
• Electron Microscope:
• This device mainly uses high speed accelerated electron beams to study very minute objects like viruses, microbes and the crystal structure of solids.
• It has a defined magnification of ~ 105

## Discussion of Exercises of NCERT Exemplar Class 12 Physics Solutions Chapter 11- Dual Nature of Radiation and Matter

1. The first section and second section of NCERT Exemplar Class 12 Physics for Chapter 11 have 13 questions which are MCQs divided into two parts ( MCQs part I and part 2) that are based on different concepts of dual nature of Radiation and Matter alongside helping you with the concepts of matter that propagates through radiation.
2. The third section has 5 questions which are very short answer type questions and based on different terminologies that include Einstein’s Photoelectric Emission, Emission of Electrons, and photoelectric effects.
3. The fourth section has 6 questions which are short answer type questions and based on the principle of dual nature of radiation, electric and magnetic field
4. The fifth section has 5 questions which are long answer type questions and based on the Davison and Germer experiment, electron microscope, De Broglie Wavelength of an Electron

The NCERT Exemplar questions are designed by DESM (Department of Education in Science and Mathematics) to induce the simplest quality problems to you which ones will test you in varying levels of difficulty on any given topic. Questions that are mentioned within the NCERT Exemplar are of immense importance from CBSE’s point of view.

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