Definition of resistance in physics

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Electrical resistance is one of the big topics in physics school lessons and is part of basic physical knowledge. This definition is intended to explain the resistance in physics simply and clearly in order to get the most out of it to prepare for the next exam or to finally give you easy access to a topic that may never have been understood before Offer.

Resistance in physics is a headache for many, but it doesn't have to be that way.
Resistance in physics is a headache for many, but it doesn't have to be that way.

What you need:

  • Resistance (R)
  • Voltage (U)
  • Current (I)

Short and simplified definition of resistance, voltage, current

  • Resistance is a material-dependent property that describes the ability to brake charge carriers. The symbol R and the unit Ohm Ω (named after the German scientist Georg Simon Ohm) are used.
  • Voltage describes the force on charge carriers; the symbol U and the unit volt V are used.
  • The current intensity describes the number of moving charge carriers in a certain time unit. The symbol I and the unit ampere A are used for this purpose.

Electrical resistance of materials

  • There are conductive and non-conductive materials, hence low and high resistance materials.
  • Through conductive materials, therefore materials with low resistance, electrical energy are easier to transport, non-conductive materials, therefore materials with high resistance, slow down charge carriers.
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  • Conductive materials include metals and carbon. Materials with low resistance such as copper, tin, silver and gold are popular in electrical engineering.
  • Ceramic, glass, plastic and paper are among the non-conductive materials and are used in the Electrical engineering used as insulators because they do not transport electrical charge and thus brake.
  • In addition to the material, the resistance is also determined by the geometric dimensions. A longer or thicker wire has a higher resistance than a shorter or thinner wire.

Relationship between resistance, voltage and amperage

  • If a material, e.g. B. A voltage is applied to a wire, a current intensity in the material can be measured, which is determined by the resistance of the wire.
  • If the voltage is increased, the amperage also increases. The resistance remains constant. Therefore, voltage and current are proportional to each other.
  • If the voltage is kept constant and the resistance is changed, e.g. B. If a thicker, thinner, longer or shorter wire or another material is used, the current strength changes. In this case the current strength is proportional to the resistance.
  • This results in the Equations R = U / I = cons., I = U / R and U = R x I.

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