NCERT Solutions for Class 12 Physics Chapter 12: Atoms

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NCERT Solutions for Class 12 Physics Chapter 12 Atoms are given in this article. Atoms are the smallest unit into which matter can be divided without the release of electrically charged particles. It also is the smallest unit of matter that has the characteristic properties of a chemical element. Atom is the basic building block of chemistry.

Unit 8 Atoms and Nuclei along with Unit 7 Dual Nature of Radiation and Matter has a weightage of 12 marks in the CBSE Board examinations. The Class 12 Physics Chapter 12 NCERT Solutions cover the concepts of Atomic Spectra, Magnetic Quantum Number, and energy levels.

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NCERT Solutions for Class 12 Physics Chapter 12

The NCERT solutions for Class 12 Physics Chapter 12: Atoms is given below.

NCERT Solutions

CBSE Class 12 Physics Chapter 12 – Topics Covered

Thomson’s Atomic Model: Every atom is a uniformly positive charged sphere of radius of the order of 10^-10 m, in which the entire mass is distributed uniformly and negatively charged electrons are randomly embedded randomly.

Limitations of Thomson’s Atomic Model

1. It couldn’t explain the origin of spectral series of hydrogen and other atoms.

2. It couldn’t explain the large angle scattering of α-particles.

Bohr Model of the Hydrogen Atom: An electron can revolve in certain non-radiating orbits for which the angular momentum of electron is an integer multiple of (h/2π).

$r_n = n^2({h^2 \epsilon_o \over \pi mZe^2})$

Hydrogen Spectrum Series: Each element emits a radiation spectrum, which is characteristic of the element itself. The spectrum is known as the line spectrum.

Hydrogen spectrum consists of 5 series – Lyman Series, Balmer Series, Paschen Series, Brackett Series, and Pfund Series.

Wave Model is based on wave mechanics. Quantum numbers are the numbers that are required to completely specify the state of the electrons.

In the presence of a strong magnetic field, the 4 quantum number are Principle quantum number, Orbital angular momentum quantum number, Magnetic quantum number, and Magnetic spin angular momentum quantum number.

Also Read:

Chapter 12 Related Articles
Structure of atom	Atomic Number	Mass Number
Subatomic Particles of Atom	Atomic Radii	Atomic Energy Level
NCERT Solution for class 12 Physics	Dalton’s Atomic Theory	Atomic Orbitals
Thomson's Atomic Model	Alpha-Particle scattering and Rutherford's Nuclear Model of Atom	Avogadro's Number
Particle Physics	Laser Light	Alpha Particle Mass

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CBSE CLASS XII Related Questions

1.
An astronomical telescope consists of two converging lenses. One of them of large aperture and large focal length is called objective lens and the other one, of smaller focal length and smaller aperture is called the eyepiece. It is used to see distant objects which are not seen clearly with naked eyes. The image formed by the objective lens acts as an object for the eyepiece and the final image produced by the eyepiece is magnified.
2.
With the help of a labelled diagram, explain the principle, construction and working of an a.c. generator.
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3.
A student sets up the circuit as shown in the figure to find the value of unknown resistance X and records a set of readings of the voltmeter and the ammeter by using the rheostat.
4.
A charged particle $+q$ in an electric field $\vec{E}$ experiences a force in the direction of the electric field. As a result, its kinetic energy changes. Similarly, the charged particle also experiences a force when it moves in a magnetic field $\vec{B}$. But this magnetic force is perpendicular to both velocity $\vec{v}$ of the charged particle and the magnetic field $\vec{B}$, so it cannot change the kinetic energy of the charged particle. Consider two charged particles 1 and 2 of masses $m$ and $\frac{m}{2}$ having charges $-q$ and $+2q$ respectively. They are accelerated from rest through the same potential difference $V$ and acquire kinetic energy $K_1$ and $K_2$. Then they enter in a region of uniform magnetic field $\vec{B}$ perpendicular to their velocities.
5.
Read the following paragraph and answer the questions that follow.
In an experiment with convex lens of focal length f, the screen is fixed at a distance D from the object. A student slowly moves the lens away from the object towards the screen and finds that she is able to form sharp image of the object for two positions of the lens. The distance between these two positions of the lens is d.
6.
Derive an expression for the capacitance of a parallel plate capacitor of plate area A and plate separation d with air present between the plates.
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