Current | Introduction to electrical engineering | Electrical engineering | Khan Academy

TL;DR

Electric current is the flow of charge and can be measured as the amount of charge passing through a given point per second.

Transcript

• [Voiceover] All right, now we're gonna talk about the idea of an electric current. The story about currents starts with the idea of charge. We've learned that we have two kinds of charges, positive and negative charge. We'll just make up two little charges like that. And we know if they're the opposite sign, that there'll be a force of attraction... Read More

Key Insights

• 🈂️ Electric current is the flow of charge and can be quantified by measuring the amount of charge passing through a given point per second.
• 🤘 Charges with opposite signs attract each other, while charges with like signs repel each other.
• 👻 Copper and silver are good conductors due to their electron configurations that allow for easy movement of electrons.
• 💐 The electron movement in a copper wire connected to a battery results in a net flow of negative charge or electric current.

Questions & Answers

Q: What determines whether charges attract or repel each other?

Charges with opposite signs attract each other, while charges with like signs repel each other. This is a fundamental concept in electrostatics.

Q: Why are copper and silver good conductors?

Copper and silver have electron configurations that include an outermost orbital with only one electron. This electron is easily pulled away and can participate in conduction, making them efficient conductors of electric current.

Q: How does an electric current flow in a copper wire connected to a battery?

When a voltage is applied across a copper wire, the positive terminal of the battery attracts the loose electrons in the wire. As electrons move towards the positive terminal, a net flow of negative charge or current is established.

Q: How does the movement of charges in a saltwater solution create current?

In a saltwater solution, the dissolved sodium ions (Na+) and chloride ions (Cl-) separate and create a net positive charge and a net negative charge, respectively. When a voltage is applied, the positive charge moves in one direction, and the negative charge moves in the opposite direction, resulting in current flow.

Summary & Key Takeaways

• Charges with opposite signs attract each other, while charges with like signs repel each other.

• Copper and silver are good conductors because they have an electron configuration that allows for easy movement of electrons.

• In a copper wire connected to a battery, electrons move from the negative terminal to the positive terminal, creating a net flow of negative charge or current.

• In a saltwater solution, the presence of dissolved ions allows for the movement of positive and negative charge, resulting in current flow.