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# Xam Idea Class 12 Physics Chapter 11 Solutions: Atoms

Xam Idea Class 12 Physics Solutions for Chapter 11 ‘Dual Nature of Matter and Radiation’ are based on the discovery of the dual nature of matter and light. In this chapter electron emission, photoelectric effect, the wave theory of light, the photon, wave nature of matter shall be explained. This chapter also covers a few experiments like Davisson and Germer experiment, the effect of intensity of light on photocurrent, the effect of potential on photoelectric current and Hertz’s observations. Our Xam Idea solutions will help you prepare this chapter from the CBSE board exam’s point of view.

Xam Idea Class 12 Physics Dual Nature of Matter and Radiation solutions is an essential study material for Class 12 Physics. This solution book covers all the topics and concepts as per the latest CBSE board exam syllabus. We have provided easy to understand solutions for all the 108 questions given in the chapter. This includes questions based on Einstein’s photoelectric effect, work function and de-Broglie hypothesis.

The solutions for Xam Idea Class 12 Physics books are prepared by the finest academic experts at Instasolv. Our solutions help you analyze and understand the questions and answers efficiently. These solutions are well-organized with an in-detailed and step-by-step explanation of all the topics. This is done to ensure that you understand the concepts more clearly.

## Important topics for Xam Idea Class 12 Physics Solutions Chapter 11 – Dual Nature of Matter and Radiation

In this section, we shall discuss a few important topics, formulas, and experiments covered in chapter 11 of Physics.

• Electric Discharge: When the electric current in an applied electric field is either released or transmitted through a medium such as gas is known as electric discharge.
• Discharge tube: Discharge tube is a tube in which when a high voltage is applied to an electron tube that contains gas or vapour at low pressure then conduction takes place.
• Cathode tube: When a voltage difference is applied between the electrodes, then a beam of electrons in a vacuum tube travelling from the negative charge to the positive charge is known as cathode ray. The negatively charged electrode is called the cathode and the positive charge electrode is called the anode.
• Work Function: A minimum quantity of energy required by the electron to escape from the metal surface is known as work function.
• Electron Emission: The minimum amount of energy required by an electron to just escape from the metal surface is known as the work function of the metal.
• Thermionic Emission: When the thermal energy helps the electrons to emit from the metal surface then it is called Thermionic emission.
• Field or Cold Cathode Emission: When with the help of a very high electric field if the electrons are emitted from a metal surface it is called field/ cold cathode emission.
• Photoelectric Emission: When with the help of electromagnetic radiations if the electrons are emitted from a metal surface it is called photoelectric emission.
• Secondary Emission: When by striking fast-moving electrons, the electrons are ejected from the metal surface then it is called secondary emission.
• Electron in Electric and Magnetic Fields and the forces experienced by it:-
• Electric field: The force FE experienced by an electron e in an electric field of strength (intensity) E is given by, FE = eE
• Magnetic field: The force experienced by an electron e in a magnetic field of strength B weber/m2 is given by, FB=Bev where v is the velocity with which the electron moves in the electric field and the magnetic field, perpendicular to the direction of motion.
• If the magnetic field is parallel to the direction of motion of the electron, then, FB = 0.
• Photoelectric Effect: We can explain the photoelectric effect with the help of photoelectric emission. So, when exposed to electromagnetic radiation the electrons emit from the surface of substances this phenomenon is called the photoelectric effect, and the emitted electrons are called photoelectrons.
• Cut Off or Stopping Potential: When for the given frequency of the incident radiation if the value of the decelerating potential at which the photoelectric current becomes zero is called cut off or stopping potential.
• Laws of Photoelectric Effect:
• For a given metal and radiation of fixed frequency, the number of photoelectrons emitted is proportional to the intensity of incident radiation.
• For every metal, there is a certain minimum frequency below which no photoelectrons are emitted, however high is the intensity of incident radiation. This frequency is called the threshold frequency.
• The maximum kinetic energy of the photoelectrons is directly proportional to the frequency of incident radiation and is independent of the intensity of incident radiation if the radiation of frequency is higher than the threshold frequency,
• The photoelectric emission is an instantaneous process.
• Photocell:
• It is an arrangement which converts light energy into electric energy.
• It works on the principle of the photoelectric effect.
• It is used in cinematography for the reproduction of sound.
• Dual Nature of Radiation: Light has dual nature. It manifests itself as a wave in diffraction, interference, polarization, etc., while it shows particle nature in the photoelectric effect, Compton scattering, etc.
• Dual Nature of Matter: As there is a complete equivalence between matter (mass) and radiation (energy) and the principle of symmetry is always obeyed, de Broglie suggested that moving particles like protons, neutrons, electrons associated with waves is known as de Broglie waves.
• If a particle of mass m is moving with a velocity v then the de Broglie wavelength is given as- • Davison and Germer Experiment: This experiment helped to confirm the existence of de Broglie waves associated with electrons.

### Exercise Discussion for Xam Idea Class 12 Physics Solutions Chapter 11: Dual Nature of Matter and Radiation

Chapter 11 – Dual Nature of Matter and Radiation, has a total of 108 solved problems in it. The problems are categorized into 4 parts: they are very short question answers (QA), short question answers part I, short question answers part II, long question answers. Each category except long QA is further divided into two parts PYQ (past years questions) and OIQ (objective inventory questionnaires).

• It consists of a total of 48 problems out of which 20 problems fall under the PYQ section and the rest 28 problems fall under the OIQ section.
• Very short QA section covers very simple questions like definitions and easy to solve problems that can be solved just by applying formulas.
• Questions like explain the work function, define the de-Broglie hypothesis, give reasons on photosensitive, explain Davison and Germer experiment, and plot a graph that falls under this part.

Short Question Answers Part I & II:

• Part I consists of a total of 28 problems from which 11 problems belong to the PYQ category and 17 belongs to the OIQ category.
• Part II consists of a total of 29 problems from which 21 problems belong to the PYQ and 8 problems belong to the OIQ. The complexity of problems asked in this section is more compared to a very short QA.
• Questions like calculate wavelength using de-Broglie, plot graphs, given reasons on different intensities and materials, calculate the work function, and Einstein’s photoelectric equation that falls under this section.