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#positive charge

3 public questions tagged with this topic.

Atomic Models - Rutherford, Thomson and Bohr

According to Thomson’s model of the atom, how is the positive charge distributed?

**Bohr's stationary orbits** defined by angular momentum quantization L = n ħ, ħ = h/2π, n=1 ground state, electron in these orbits does not radiate despite acceleration, contrary to classical EM theory which predicts atom collapse due to energy loss via radiation, Bohr postulates to explain observed stability and discrete spectra. In Thomson’s model, the positive charge is uniformly distributed throughout the volume of the atom, with electrons embedded in it like seeds in a watermelon. Using E_n = -13.6/n² eV, r_n = n² a₀, L = n h/2π, R = R₀ A^¹/³, BE = Δm c² and 1 u = 931.5 MeV, evaluation y

Ref: NCERT > Physics Book > Atoms and Nuclei > Atomic Models - Rutherford, Thomson and Bohr

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Magnetic Force on Moving Charge - Lorentz Force and Motion

What is the direction of the magnetic force on a positive charge moving parallel to a uniform magnetic field?

**Motion of charged particle perpendicular to uniform B** is circular because force F ⊥ v, no work done, speed constant, radius r = m v/(q B), period T = 2π m/(q B) independent of v. If v has component parallel to B, helical path results, pitch = v_parallel·T. The magnetic force is given by F = q (v × B) . If the velocity v is parallel to the magnetic field B , the angle between them is 0° , so sin 0° = 0 , and the force magnitude is zero. Thus, there is no force. Using F = q v B sinθ, F

Ref: NCERT > Physics Book > Moving Charge and Magnetism > Magnetic Force on Moving Charge - Lorentz Force and Motion

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Coulomb's Law and Force Between Point Charges

What ensures that the electric field lines from a positive point charge always point radially outward?

**Coulomb's law** gives force between point charges as F = k·|q₁q₂|/r², k = 1/(4π ε₀) = 9×10⁹ N·m²/C², directed along line joining charges. Like charges repel, opposite attract, magnitude scales with product of charges and inverse square of separation r². The positive charge generates a repulsive force on a positive test charge, as per Coulomb’s law. Due to the spherical symmetry of a point charge, the field is directed radially outward, reflecting the repulsion and symmetry of the charge distribution. Substituting values gives Repulsion, which matches expected magnitude for this electrostatic

Ref: NCERT > Physics Book > Electric Charges and Fields > Coulomb's Law and Force Between Point Charges

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