NCERT Solutions For Class 12 Physics Chapter 5: Magnetism and Matter

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Jasmine Grover

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NCERT Solutions for class 12 physics chapter 5 Magnetism and Matter are given in this article with a detailed explanation. Magnetism is a force by virtue of which a metal is attracted to certain materials, which are known as magnets. These days magnets have a lot of applications in areas such as an electric bell, telephone, radio, loudspeaker, motors, fans, screwdrivers, etc.

The chapter has a weightage of 5 to 6 marks in the CBSE Class 12 Physics Examination. The NCERT Solutions for Class 12 Physics Chapter 5 covers concepts of the dipole moment of a magnet, permanent magnets, classification of magnetic materials, etc. 

Download PDF: NCERT Solutions for Class 12 Physics Chapter 5


NCERT Solutions for Class 12 Physics Chapter 5

NCERT solutions for class 12 physics chapter 5: Magnetism and Matter are given below. 


Class 12 Physics Chapter 5 Magnetism and Matter – Important Concepts

  • Magnetic field lines are the imaginary lines along which the North Magnetic move.
The larger the number of magnetic field lines per unit area, the stronger the magnetic field will be.
  • When a magnet placed in a uniform magnetic field B experiences a dipole moment m, then it experiences a force, torque, and potential energy.
  1. Force = zero
  2. Torque = m*B
  3. Potential energy = m*B. 
  • Magnetic Materials are classified as Diamagnetic, paramagnetic, and ferromagnetic. χ refers to the magnetic sensitivity of the material.

  1. Diamagnetic materials – negative and small χ 
  2. Paramagnetic materials – positive and small χ
  3. Ferromagnetic materials – large χ.
  • The magnetic field of a solenoid with a radius, carrying I current at distance r on the axis is given by: 

\(B = {\mu_0 \over 4\pi} {2m \over r^3}\)
  • In the above formula, m refers to the magnetic moment of the solenoid that is given by – 

\(m = n(2l)(\pi a^2)\)

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CBSE CLASS XII Related Questions

  • 1.
    Two small identical metallic balls having charges \( q \) and \( -2q \) are kept far at a separation \( r \). They are brought in contact and then separated at distance \( \frac{r}{2} \). Compared to the initial force \( F \), they will now:

      • attract with a force \( \frac{F}{2} \)
      • repel with a force \( \frac{F}{2} \)
      • repel with a force \( F \)
      • attract with a force \( F \)

    • 2.
      Differentiate between inductive reactance, capacitive reactance and impedance of an ac circuit.
      An ideal inductor and an ideal capacitor are connected in series across an ac voltage. Plot a graph showing variation of net reactance of the circuit with frequency of the applied ac voltage.


        • 3.
          The magnetic field in a plane electromagnetic wave travelling in glass (\( n = 1.5 \)) is given by \[ B_y = (2 \times 10^{-7} \text{ T}) \sin(\alpha x + 1.5 \times 10^{11} t) \] where \( x \) is in metres and \( t \) is in seconds. The value of \( \alpha \) is:

            • \( 0.5 \times 10^3 \, \text{m}^{-1} \)
            • \( 6.0 \times 10^2 \, \text{m}^{-1} \)
            • \( 7.5 \times 10^2 \, \text{m}^{-1} \)
            • \( 1.5 \times 10^3 \, \text{m}^{-1} \)

          • 4.
            Write any two features of nuclear forces.


              • 5.
                A part of a wire carrying \( 2.0 \, \text{A} \) current and bent at \( 90^\circ \) at two points is placed in a region of uniform magnetic field \( \vec{B} = -0.50 \, \hat{k} \, \text{T} \), as shown in the figure. Calculate the magnitude of the net force acting on the wire.


                  • 6.
                    A circular coil of 100 turns and radius \( \left(\frac{10}{\sqrt{\pi}}\right) \, \text{cm}\) carrying current of \( 5.0 \, \text{A} \) is suspended vertically in a uniform horizontal magnetic field of \( 2.0 \, \text{T} \). The field makes an angle \( 30^\circ \) with the normal to the coil. Calculate:
                    the magnetic dipole moment of the coil, and
                    the magnitude of the counter torque that must be applied to prevent the coil from turning.

                      CBSE CLASS XII Previous Year Papers

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