Electrical Engineering BMT & UFC › Ideal Components

Ideal Conductor

Description

The lines connecting components in a circuit diagram represent ideal conductors with a resistance of R_Leiter = 0 Ω. So current flows unhindered through the ideal conductors. In a real circuit, wires and cables come quite close to the ideal conductor, because their ohmic resistance is often very small, in the milliohm range.

On circuit boards, ideal conductors are realised by copper traces.

Power and energy

For an ideal conductor, the following applies:

\[ \begin{gathered} R = 0\,\Omega \\[4pt] U = R \cdot I = 0\,\Omega \cdot I = 0\,\mathrm{V} \\[4pt] P = U \cdot I = 0\,\mathrm{V} \cdot I = 0\,\mathrm{W} \\[4pt] W(t) = \int p(t)\,dt = 0\,\mathrm{J} \end{gathered} \]

Let us consider an ideal conductor that connects an LED to the battery in a torch. Current flows through the conductor when the switch of the torch is closed. The magnitude of the current is determined by the battery and the LED. How to calculate this comes a little later. The current flowing through an ideal conductor is always determined by the connected circuit.

The voltage across the ideal conductor is always 0 V, so no electrical power is dissipated in it. The ideal conductor therefore does not get warm when current flows through it. No electrical energy is converted into heat, as is the case with an ohmic resistor.

The resistance of a real conductor is so small that the assumptions in the formulas above can usually also be made in reality. Normally, other resistances in circuits are so much higher that real conductors have no influence on the function of a circuit.

Use in a circuit

The conductor connects components to each other. In a torch, for example, it is installed between the battery and the LED.

Overhead power lines

In a power plant, coal is burned around the clock. The (thermal) energy released in this way separates an enormous amount of charge. The charge in the power plant strives for charge balance. The path for charge balancing is led via overhead lines into your house. There the current flows, for example, through your washing machine. Afterwards it flows back to the power plant. Charge balancing only takes place in the power plant. So conductors are used to make the effect of the current possible at a different place from the one where the charge was originally separated.