What is an ohm 1

Electrical resistance R

Resistors play a very important role in electronics. In addition to the classic resistors, every component has a resistance value that influences voltages and currents in circuits.
The electrical resistance is also referred to as ohmic resistance.

The effect of an electrical resistance on the electrical current has to be imagined as follows:

  • The movement of free charge carriers inside a conductor has the consequence that the free charge carriers collide with atoms and their flow is disturbed.
  • This effect is called resistance, which has the property of limiting the current in a circuit.
  • The collision of the charge carriers with the atoms also has a thermal effect. The component in question becomes warm or even hot. If it gets too hot it can break. Then the number of charge carriers and thus the electrical current was too great.

More information about resistance in electronics


1000000 Ω = 1 MΩ (megohms)
100000 Ω = 100 kΩ (kiloohms)
10000 Ω = 10 kΩ (kiloohms)
1000 Ω = 1 kΩ (kiloohms)
100 Ω (ohms)
10 Ω (ohms)
1 Ω (Ohm)
0.1 Ω = 100 mΩ (milliohms)

The unit of measurement for electrical resistance is ohm with the abbreviation “Ω”. Omega is a letter from the Greek alphabet.
Large resistances are given in kiloohms (kΩ) or megaohms (MΩ). Hardly measurable resistances are in the range of milliohms (mΩ).

Formula symbol

R: electrical resistance
r: dynamic resistance
R.1 : Resistance 1

The symbol for electrical resistance is the capital "R". It stands for the English name Resistor or Resistance.
Deviating from this, there are different spellings in upper and lower case with additional symbols that have a specific meaning. A number or letter as an index identify a specific voltage in a circuit.

Formula for calculation

Measuring the ohmic resistance

Basically, the following rules apply:

  • Measurement parallel to the component
  • The component must be voltage-free
  • Component must not be interconnected
  • Measurement only makes sense on a normal resistor

The value of the ohmic resistance is best determined with a digital multimeter (multimeter) in order to avoid reading errors and inaccuracies.
When measuring with an ohmmeter, the component to be measured must not be connected to a voltage source during the measurement. The component to be measured must be unsoldered from a circuit at least on one side. Otherwise components lying parallel will influence the measurement result.

Resistors in electronics

Resistors in electronic circuits

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