Sign convention for passive components | Electrical engineering | Khan Academy

TL;DR

Passive components do not create or amplify power. The sign convention for these components dictates the labeling of voltage and current to ensure correct application of Ohm's law.

Transcript

• [Voiceover] Today we're gonna talk about the sign convention for passive components. It's a big mouthful, but it's a fairly simple idea. Well first of all, let's look at this word passive. Passive is the way we describe components that do not create power or components that do not amplify signals. So particularly resistors, as we have one here. D... Read More

Key Insights

• ✊ Passive components, such as resistors, capacitors, and inductors, do not create or amplify power in a circuit.
• 🤘 The sign convention for passive components is used to label voltage and current in a circuit, ensuring correct application of Ohm's law.
• ⚡ When labeling voltage and current for a resistor, the positive current flows from the positive voltage end to the negative voltage end.
• 🤘 The sign convention is applicable to all passive components, including capacitors and inductors.
• ➕ The plus sign indicates the direction of the current flow in relation to the positive terminal or end of the component.
• 👻 The sign convention allows for consistent naming of voltages and currents in complex circuits.
• 🤘 Understanding the sign convention is crucial for accurate analysis and calculations using Ohm's law.

Questions & Answers

Q: How are passive components defined?

Passive components are those that neither create power nor amplify signals, such as resistors, capacitors, and inductors.

Q: Can a battery be considered a passive component?

Yes, although it provides power, a battery is considered a passive component because it cannot amplify a signal.

Q: According to the sign convention, how is the current labeled when a positive voltage is applied to a resistor?

When the positive voltage is applied to a resistor, the current flows from the positive end to the negative end of the resistor.

Q: How is the current labeled when a resistor is oriented sideways?

Regardless of the orientation, the current still flows into the positive terminal or the positive end of the resistor.

Summary & Key Takeaways

• Passive components such as resistors, capacitors, and inductors do not create or amplify power.

• The sign convention for passive components determines the direction of current flow based on the labeling of voltage.

• In the case of a resistor, the current flows from the positive voltage end to the negative voltage end.