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.
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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2.
The resistance of a metal wire at $ 20^\circ \text{C} $ is $ 1.05 \, \Omega $ and at $ 100^\circ \text{C} $ is $ 1.38 \, \Omega $. Determine the temperature coefficient of resistivity of this metal.
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3.
Two metal spheres of radii $r_1$ and $r_2$ ($> r_1$) having charges $q_1$ and $q_2$ respectively kept in air, are brought in contact. Which of the following statements is not correct ?
- The total charge of the two spheres is conserved.
- Both spheres attain the same potential.
- The final potential of the system equals $\frac{1}{4\pi\epsilon_0} \frac{(q_1 + q_2)}{(r_1 + r_2)}$
- The final potential of the system equals $\frac{1}{4\pi\epsilon_0} \frac{(q_1 + q_2) (r_1 + r_2)}{r_1 r_2}$
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4.
Consider a cylindrical conductor of length $ l $ and area of cross-section $ A $. Current $ I $ is maintained in the conductor and electrons drift with velocity $ \vec{v}_d \, (|\vec{v}_d| = \frac{eE}{m} \tau) $, where symbols have their usual meanings. Show that the conductivity of the material of the conductor is given by \[ \sigma = \frac{n e^2 \tau}{m}. \]
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5.
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.
6.
Two air-filled capacitors of capacitances $C_1$ and $C_2$ are connected in parallel with a dc battery. After the capacitors are fully charged, a slab of dielectric constant K is inserted between the plates of each capacitor. How will the (i) charge on each capacitor and (ii) energy stored in the capacitor affected after the slab is introduced.
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