# ← (nm04)電磁感應 Electromagnetic Induction (I) →

## Pre-Amble: Michael Faraday (22 September 1791 – 25 August 1867)

Born in England, Michael Faraday (22 September 1791 – 25 August 1867) contributed to the fields of electromagnetism and electrochemistry becoming one of history's most influential scientists and engineers. Being born in a poor family, he received little formal education, educating himself by reading books.

Father of Nanoscience and Nanotechnology. In 1847 he discovered that the optical properties of gold colloids (now called gold nanoparticles) differed from those of the corresponding bulk metal. This was the first reported observation of the effects of quantum size.

When asked by the Prime Minister of England what the usefulness of electricity would be, Faraday replied, "Why, Sir, there is every possibility that you will soon be able to tax it!"

His strong faith in Jesus influenced his life strongly. When offered a knighthood, he refused believing it was against Biblical teaching to accumulate riches and pursue worldly reward. When asked by the British government to advise on the production of chemical weapons, he likewise refused.

## Key Points

Flux Φ $$\mathscr E \,\,\, (emf)$$ $$\Phi_E = \iint \mathbf {\vec E} \, \cdot d \mathbf {\vec A}$$ $$\Phi_M = \iint \mathbf {\vec B} \, \cdot d \mathbf {\vec A}$$ $$\mathscr E = W_{chem} / q \, \, (電池)$$ $$\mathscr E = - { {d \Phi_m} \over {dt}}$$ $$\mathscr E = \oint \color{fuchsia} {\mathbf {\vec E}}(t) \, \cdot \, d \, \mathbf {\vec s} = - { {d \Phi_m} \over {dt}} = - {d \over dt} \iint \color{fuchsia} { \mathbf {\vec B}}(t) \, \cdot d \mathbf {\vec A}(t)$$ 目前電場和磁場是一个方便的数学方法， 现在是物理學Up to this point, fields have been useful mathematical tools to help us do calculations,Faraday discovered that these fields really do physically exist. (This idea was rejected by his fellow scientists. Faraday did not live to see the eventual acceptance of this idea by the scientific community.)

## Selected Problems on Magnetism

29.60 An electron in a cathode-ray tube is accelerated through a potential difference of 10 kV, then passes through the d = 2.0-cm-wide region of uniform magnetic field.What field strength will deflect the electron by θ = 10.0 degrees?

29.30 For your senior project, you would like to build a cyclotron that will accelerate protons to 10% of the speed of light. The largest vacuum chamber you can find is 44 cm in diameter.

29.5 Magnetic Field from Moving Charge. What is the magnetic field at the position of the dot in the figure? Give your answer as a vector.

## 103-2 Finish Previous PPT

103-2 (fr 32-100); 106-2 (fr 29-128)

## Knight Chapter 30

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