Faraday's Law Introduction | Physics | Khan Academy

TL;DR

A changing magnetic field induces a current in a stationary loop of wire, causing the motion of charges.

Transcript

• [Voiceover] In other videos we talk about how a current flowing through a wire can induce a magnetic field. And we're going to talk about in this video is how we can go the other way. How a change in a magnetic field can affect or induce a current in a loop of wire. So we're gonna be going from a change, change in and actually we're gonna focus o... Read More

Key Insights

• 🔁 A stationary loop of wire in a magnetic field does not produce a current unless there is a change in the magnetic flux through the loop.
• 💱 The direction of the induced current depends on the direction of the change in the magnetic flux.
• 🏑 The induction of current can be achieved by changing the magnetic field, moving the loop, or increasing its area.
• 🔁 Faraday's Law states that a changing magnetic flux through a loop induces a current in the wire.

Questions & Answers

Q: How can a current be induced in a loop of wire in a magnetic field?

A current is induced in a loop of wire when there is a change in the magnetic flux through the loop. The change can occur by increasing the magnetic field outward, moving the loop, or increasing its area.

Q: Does a stationary loop of wire in a static magnetic field produce a current?

No, a stationary loop of wire in a static magnetic field does not produce a current unless there is a change in the magnetic flux through the loop.

Q: How does increasing the magnetic flux outward through the loop induce current flow?

When the magnetic flux through a loop of wire is increased outward, it creates a change in the flux. This change induces a voltage, causing an electro-motive force that leads to the flow of current in a clockwise direction.

Q: What happens to the current flow if the magnetic flux decreases inward through the loop?

If the magnetic flux decreases inward through the loop, it creates a change in the flux in the opposite direction. This change induces a voltage that causes the current to flow in a counterclockwise direction.

Summary & Key Takeaways

• A static loop of wire in a magnetic field does not produce a current unless there is a change in the magnetic flux through the loop.

• Increasing the magnetic flux outward through the loop induces a clockwise current flow, while decreasing the magnetic flux induces counterclockwise current flow.

• Moving the loop or increasing its area also changes the magnetic flux, leading to the induction of a current.