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Magnetic Properties of Matter — Physics STD 12 Science — Question

Gujarat BoardEnglish MediumSTD 12 SciencePhysicsMagnetic Properties of Matter4 Marks
Question
When a ferromagnetic material goes through a hysteresis loop, its thermal energy is increased. Where does this energy come from?
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Answer

When a ferromagnetic material is taken through the cycle of magnetisation, magnet dipoles of the material orient and reorient with time. This molecular motion within the material results in the production of heat, which increses thermal energy of material.

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Niels Bohr introduced the atomic Hydrogen model in 1913. He described it as a positively charged nucleus, comprised of protons and neutrons, surrounded by a negatively charged electron cloud. In the model, electrons orbit the nucleus in atomic shells. The atom is held together by electrostatic forces between the positive nucleus and negative surroundings.

Bohr correctly proposed that the energy and radii of the orbits of electrons in atoms are quantized, with energy for transitions between orbits given by
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  1. De Broglie wavelengths
  2. Wave frequencies
  3. Quantum numbers
  4. Diffraction patterns.
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  2. Inversely proportional to $\sqrt{\text{n}}$
  3. Inversely proportional to $n^2$
  4. Inversely proportional to $n^3$
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  1. $\frac{\text{h}}{2\pi}$
  2. $\frac{\text{h}}{\pi}$
  3. $\frac{\text{3h}}{2\pi}$
  4. $\frac{\text{2h}}{\pi}$
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  3. Infinite energy
  4. Zero energy
  1. Which of the following postulates of the Bohr model led to the quantization of energy of the hydrogen atom?
  1. The electron goes around the nucleus in circular orbits.
  2. The angular momentum of the electron can only be an integral multiple of $\frac{\text{h}}{2\pi}$.
  3. The magnitude of the linear momentum of the electron is quantized.
  4. Quantization of energy is itself a postulate of the Bohr model.
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