How does the current increase when the resistance increases

At the beginning of the 19th century, the mathematician, physicist and philosopher Georg Simon Ohm experimented with different materials. Among other things, he examined the materials for their electrical conductivity and discovered that not every material conducts electricity equally well, e.g. that copper transports electricity better than steel. Ohm also discovers that short and thick cables carry more current than long and thin ones. He called the force that the electrons hinder the flow of electricity "resistance", which is why the unit for it was named after him.

He found out more, however. Up until the Ohms experiments, the common opinion was that current strength and electrical voltage are independent quantities. Georg Simon Ohm, however, recognizes the mathematical relationship that the relationship between the electrical current strength and the associated electrical voltage is constant and the constant forms the electrical resistance. This relationship described by Ohm is a very important finding and has been part of the fundamentals of electrical engineering ever since.

Ohm formulated what was named after him Ohm's law.

  • This shows that the voltage and the current are proportional. If the resistance increases, the voltage and current intensity decrease proportionally. When the resistance drops, these two quantities increase proportionally.
  • If the voltage is increased with the same resistance, the current intensity increases automatically and vice versa.
  • If voltage and current increase or decrease proportionally, this in turn does not change anything in the resistance (constant). With a voltage / current pair of 200 volts / 10 amps you have the same resistance as with 20 volts / 1 ampere.
  • It can also happen that the voltage and the resistance are increased, e.g. due to a change in the temperature of the conductor due to the flow of current. In this case, the increase in voltage does not lead to a proportional but less than proportional increase in the current, because the resistance increases. Viewed from the other side, the voltage increases disproportionately as the current and resistance increase.

From all the conclusions one can derive the following formulas from Ohm's law: