Faraday's Law example | Physics | Khan Academy

TL;DR

This video explains how to calculate the change in flux, induced voltage, and current direction using Faraday's Law in a simple example.

Transcript

• So we have something interesting going on. I have this ring of conductor right here, this square ring, it has a resistance of two ohms, we see that it is two meters by two meters so the area of this ring would be four square meters and we see a magnetic field going through the surface defined by the ring and it's constant, it's a constant magneti... Read More

Key Insights

• 💱 The change in flux can be determined by subtracting the initial flux from the final flux.
• 💱 Faraday's Law relates the induced voltage to the change in flux and the time it takes for the change to occur.
• ⚡ The magnitude of the induced current can be calculated by dividing the induced voltage by the resistance.
• 🫱 The direction of the induced current can be determined using the right hand rule, which shows that it will flow in a clockwise direction in this example.
• 🏑 Lenz's law states that the induced current will generate a magnetic field that opposes the change in the original magnetic field.

Questions & Answers

Q: What is the initial and final flux for the square ring?

The initial flux is 20 tesla meter squared, and the final flux is 40 tesla meter squared.

Q: How is the voltage induced calculated?

According to Faraday's Law, the voltage induced is equal to the change in flux divided by the change in time. In this example, it is -5 volts.

Q: What is the formula for Faraday's Law?

The formula is V = -N * (change in flux / change in time), where N is the number of loops or surfaces defined by the conductor.

Q: How is the magnitude of the induced current determined?

The magnitude of the current is calculated by dividing the induced voltage by the resistance. In this case, it is 2.5 amperes.

Summary & Key Takeaways

• The video discusses a square ring of conductor with a resistance of 2 ohms and a constant magnetic field of 5 teslas going through its surface.

• Over four seconds, the magnetic field doubles to 10 teslas, resulting in a change in flux.

• Using Faraday's Law, the video calculates the change in flux, the induced voltage, and the magnitude and direction of the current.