2./kloc-at the end of 0/9, electricity rose, providing a way to destroy atoms. When discharged in a low-pressure gas, the atom splits into two charged parts. 1897, when Thomson of the United States studied two parts of charge, he found that one part was negatively charged (called electrons) and the other part was positively charged.

3. After Oster discovered the magnetic effect of current, Ohm began to study what laws the current of the wire itself followed. Inspired by the law of heat flow (the heat flow between two points in a heat conducting rod is proportional to the temperature difference between the two points), he speculated that the current between two points in a wire may be proportional to some driving force between the two points. Ohm called this unknown driving force "test force", and now it is called potential difference or voltage. On the basis of this idea, Ohm did a series of experiments, but the experiments encountered many difficulties. At first, Ohm used voltaic pile as power supply, and the effect was not ideal. Later, the newly invented thermoelectric battery was used as the power supply, and a stable current was obtained. The second difficulty is the measurement of current. At first, ohm used the thermal effect of current to measure current through thermal expansion and contraction, but it did not achieve ideal results. Later, he skillfully used the magnetic effect of current to design the current torsion balance, which effectively solved this problem. Ohm uses a stranded wire to hang a horizontally placed magnetic needle, and the conductor to be tested is placed below and parallel to the magnetic needle, with bismuth-copper thermoelectric battery as power supply. Ohm did many experiments repeatedly, and got the earliest form of Ohm's law, which was published in the German Journal of Chemistry and Physics at 1826. The topic of this paper is "Determination of the Law of Metal Conductivity".

1827, he published his most famous book "Mathematical Discussion of galvani Circuits", in which he listed formulas, clearly pointing out that the current in galvani's circuit is directly proportional to the total voltage of the circuit and inversely proportional to the total resistance of the circuit, where S is the current intensity (I) in the conductor, A is the voltage at both ends of the conductor (U) and L is the resistance (R) of the conductor. So, this is today's part.

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