Category: Part 3: Electricity
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Problem 3.125 — Self-inductance of a toroid
Problem Statement Solve the magnetic field/force problem: Irodov Problem 3.125. $$L = \frac{\mu_0 N^2 h}{2\pi}\ln\frac{b}{a} \approx 150\,\mu\text{H}$$ for given dimensions. Given Information Current $I$ or charge $q$ and velocity $v$ as given Geometry (straight wire, loop, solenoid) as specified Permeability of free space $\mu_0 = 4\pi\times10^{-7}\,\text{T m A}^{-1}$ Physical Concepts & Formulas Magnetic fields arise…
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Problem 3.45 — Gauss law: non-uniform charge distribution
Problem Statement Determine the electric field for the configuration described: Irodov Problem 3.45. For $\rho = \rho_0(1-r/R)$: inside $E = \rho_0(r/3-r^2/4R)/\varepsilon_0$; outside $E = \rho_0 R^3/(12\varepsilon_0 r^2)$. Given Information Geometry and charge distribution as given in the problem Permittivity of free space $\varepsilon_0 = 8.85\times10^{-12}\,\text{C}^2\text{N}^{-1}\text{m}^{-2}$ Coulomb constant $k = 1/(4\pi\varepsilon_0) = 9\times10^9\,\text{N m}^2\text{C}^{-2}$ Physical Concepts…
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Problem 3.77 — Resistivity: metals vs semiconductors
Problem Statement Irodov Problem 3.77. Given Information All quantities, constants, and constraints stated in the problem above Physical constants used as needed (see Concepts section) Physical Concepts & Formulas This problem draws on fundamental physical principles. The key is to identify which conservation law or field equation governs the system, then apply it systematically. Dimensional…
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Problem 3.122 — Ampere’s law in magnetic media
Problem Statement Solve the magnetic field/force problem: Irodov Problem 3.122. $\oint\mathbf{H}\cdot d\mathbf{l} = I_{\text{free}}$. Boundary: $H_{1t}=H_{2t}$ (no free surface current); $B_{1n}=B_{2n}$ always. Given Information Current $I$ or charge $q$ and velocity $v$ as given Geometry (straight wire, loop, solenoid) as specified Permeability of free space $\mu_0 = 4\pi\times10^{-7}\,\text{T m A}^{-1}$ Physical Concepts & Formulas Magnetic…
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Problem 3.257 — Electromagnetic induction
Problem Statement Solve the magnetic field/force problem: Irodov Problem 3.257 — Electromagnetic induction. This problem belongs to the section on Electromagnetic induction . Key principles: Faraday: $\mathcal{E} = -d\Phi/dt$; Lenz; motional EMF; inductance The solution proceeds by identifying the relevant physical configuration, applying the governing law Given Information Current $I$ or charge $q$ and velocity…
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Problem 3.161 — Magnetostatics and magnetic forces
Problem Statement Solve the magnetic field/force problem: Irodov Problem 3.161 — Magnetostatics and magnetic forces. Key law: $B_{\text{wire}} = \mu_0 I/(2\pi r)$, torque $\tau = mB\sin\theta$, force $F = qvB\sin\theta$ This problem from the Magnetostatics and magnetic forces section requires applying the governing equation with the given geometry and nume Given Information Current $I$ or…
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Problem 3.46 — Electrostatic shielding in a cavity
Problem Statement Irodov Problem 3.46. Given Information All quantities, constants, and constraints stated in the problem above Physical constants used as needed (see Concepts section) Physical Concepts & Formulas This problem draws on fundamental physical principles. The key is to identify which conservation law or field equation governs the system, then apply it systematically. Dimensional…
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Problem 3.78 — Delta-Y conversion
Problem Statement Irodov Problem 3.78. Given Information All quantities, constants, and constraints stated in the problem above Physical constants used as needed (see Concepts section) Physical Concepts & Formulas This problem draws on fundamental physical principles. The key is to identify which conservation law or field equation governs the system, then apply it systematically. Dimensional…
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Problem 3.123 — Magnetic field in gap of toroid
Problem Statement Solve the magnetic field/force problem: Irodov Problem 3.123. Magnetic circuit: $NI = H_{\text{core}}l_c + H_{\text{gap}}l_g$; $B$ continuous. Result: $B \approx 0.42\,\text{T}$. Given Information Current $I$ or charge $q$ and velocity $v$ as given Geometry (straight wire, loop, solenoid) as specified Permeability of free space $\mu_0 = 4\pi\times10^{-7}\,\text{T m A}^{-1}$ Physical Concepts & Formulas…
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Problem 3.258 — Electromagnetic induction
Problem Statement Solve the magnetic field/force problem: Irodov Problem 3.258 — Electromagnetic induction. This problem belongs to the section on Electromagnetic induction . Key principles: Faraday: $\mathcal{E} = -d\Phi/dt$; Lenz; motional EMF; inductance The solution proceeds by identifying the relevant physical configuration, applying the governing law Given Information Current $I$ or charge $q$ and velocity…