________________
rubbing are due to the transfer of charges only from one
body to other. 2. Coulomb's law in electrostatics holds only for stationary
charges, which are points in size. 3. When the same two charges located in air are placed in
a dielectric medium without altering the distance between
them, electrostatic force always decreases. 4. A system of charge is said to be in equilibrium, if the net
force experienced by each charge of the system is zero. 5. Electrostatic force between two charges is not affected by
the presence of a third charge in their space." Ibid. p.4 (218 is GELG 291 Gla! 24490 s) “A polythene piece rubbed rubbed with wool is found to have a negative charge 3 x 107 C. Estimate the number of electrons transferred from wool to polythene.” Sol. Here, total charge transferred, q = - 3 x 107 C Charge on an electron, e = - 1.6 × 10-19 C From quantization of charge, 9 = ne Therefore, number of electrons transferred,
- 3 x 10-7
(c)
e
- 1.6 x 10-19 = 1.875 x 1012
46. (a)
Gujarat State Board of Text books, Text book of Physics (Part-2), Std. xii, pp. 1,2— "The discoveries and the early understanding of the electrical and the magnetic phenomena, developed independently of each other. The pioneering experimental studies of early scientists like Oersted, Rowland and Faraday established the connections between the magnetic fields and the electric currents. A complete synthesis of the two groups of phenomena was achieved by the theoretical works of Maxwell and Lorentz, the synthesis being now called the electromagnetic phenomena. It was this deeper understanding of the electromagnetic phenomena, that led to the identification of light as electromagnetic waves. Further technological developments in the production, propagation and detection of the electromagnetic radiation's have revolutionized our global communication techniques.
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