# How Does Lenz's Law Explain Magnetic Field Directions?

• bluesteels
In summary, the conversation discusses the direction of the magnetic field for a top and bottom wire and the use of the right hand rule to determine its direction. It mentions that for an infinite straight wire, the magnetic field is always perpendicular and will change direction if the current is reversed.
bluesteels
Homework Statement
The current I in a long, straight wire is constant and is directed
toward the right as in Fig. E29.16. Conducting loops A, B, C, and D are moving, in the directions shown, near the wire. (a) For each loop, is the direction of the induced current clockwise or counterclockwise, or is the induced current zero? (b)
Relevant Equations
None equation

This the images of the figure. I am confused on why is the magnetic field for the top wired is out and the bottom is in. Is that the general rule??

Moreover what if the wired is point to the left instead of right is the magnetic field still out of the page.

You can find which way the magnetic field points using an appropriate right hand rule.

For an infinite straight wire, the magnetic field is always perpendicular to the wire itself and to the separation from the wire. If you change the direction of the current, the direction of the field will also be reversed.

## 1. What is Lenz' Law?

Lenz' Law is a fundamental law in electromagnetism that states that the direction of an induced current in a conductor will always oppose the change in magnetic field that caused it.

## 2. Who discovered Lenz' Law?

Lenz' Law was discovered by Russian physicist Heinrich Lenz in 1834.

## 3. How is Lenz' Law related to Faraday's Law?

Lenz' Law is closely related to Faraday's Law of induction. Faraday's Law states that a changing magnetic field will induce an electric current in a conductor. Lenz' Law explains the direction of this induced current.

## 4. What are some real-life applications of Lenz' Law?

Lenz' Law has many practical applications, such as in generators, motors, and transformers. It is also used in electromagnetic braking systems and in the design of metal detectors.

## 5. How can Lenz' Law be demonstrated in a simple experiment?

A simple experiment to demonstrate Lenz' Law is to drop a magnet through a copper pipe. As the magnet falls, it creates a changing magnetic field, which induces an opposing current in the copper pipe. This current creates a magnetic field that slows down the magnet's fall, demonstrating Lenz' Law in action.

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