/*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none} Problem 33 The plane of a flat, circular lo... [FREE SOLUTION] | 91Ó°ÊÓ

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The plane of a flat, circular loop of wire is horizontal. An external magnetic field is directed perpendicular to the plane of the loop. The magnitude of the external magnetic field is increasing with time. Because of this increasing magnetic field, an induced current is flowing clockwise in the loop, as viewed from above. What is the direction of the external magnetic field? Justify your conclusion.

Short Answer

Expert verified
The external magnetic field is directed downward.

Step by step solution

01

Understand the Problem

The problem discusses a circular loop of wire with an external magnetic field increasing over time. This causes an induced current in the loop according to Faraday's Law of Induction. We need to find out the direction of the external magnetic field.
02

Apply Lenz's Law

Lenz's Law states that the direction of the induced current in a loop will be such that it opposes the change in magnetic flux through the loop. Since the induced current is clockwise, the induced magnetic field must be opposing an increase in the external magnetic field entering the loop.
03

Determine the Direction of Induced Magnetic Field

A clockwise current, as seen from above, would create an induced magnetic field pointing downward, opposing the increase in the external field.
04

Infer the External Magnetic Field Direction

Since the induced magnetic field is downward because of the clockwise induced current, the external magnetic field must be in the downward direction as it increases through the loop when viewed from above.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Faraday's Law of Induction
Faraday's Law of Induction is a fundamental principle explaining how a change in the magnetic field within a closed loop of wire induces an electromotive force (EMF). This phenomenon forms the basis for many electrical technologies. The law states that the induced EMF in any closed circuit is equal to the negative of the rate of change of the magnetic flux through the circuit. In simpler terms, when the magnetic field around a conductor changes, it induces a voltage which can cause a current to flow if there is a closed path.
Consider a flat, circular loop of wire. If the magnetic field around this loop changes, say it's getting stronger as in the scenario described, an EMF will be induced. The strength of this EMF depends on both the rate of change of the magnetic field and the size of the loop. A faster change or a larger loop would result in a greater induced EMF.
Understanding Faraday's Law is crucial to solving problems where magnetic fields interact with conducting loops, especially in determining the direction and magnitude of induced currents.
Lenz's Law
Lenz's Law gives us insight into the direction of the induced current, especially when a magnetic field through a loop is changing. The law states that the direction of the induced current will always be such that it creates a magnetic field opposing the change that caused it.
This might sound a little tricky, but think of it as nature's way of keeping balance. For the given problem, the magnetic field is increasing, leading to an induced current flowing in a direction to oppose that increase. If you observe from above and see a clockwise current, like in our exercise, Lenz's Law tells us that this current is fighting against the increasing upward-magnetic field, indicating its own created field must point down.
Lenz's Law provides the practical method to determine the induced current's direction and helps justify the conservation of energy in electromagnetic processes.
Magnetic Fields
Magnetic fields are invisible forces around magnets and current-carrying wires that can exert forces on other magnets and wires. They are represented by magnetic field lines, which show the direction of the field and, in illustration, closer lines indicate a stronger field.
In the context of the exercise, the external magnetic field is changing—specifically, its magnitude is increasing over time. This increasing magnetic field passing through the wire loop induces a current as described by Faraday's Law. The direction of this external field is inferred based on the induced current's behavior, depicted by Lenz's Law.
For the loop problem, imagining it visible in three dimensions helps: the magnetic field lines push through the loop perpendicularly, creating an environment where the laws of induction and the resulting currents interact visibly.

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Most popular questions from this chapter

Magnetic resonance imaging (MRI) is a medical technique for producing pictures of the interior of the body. The patient is placed within a strong magnetic field. One safety concern is what would happen to the positively and negatively charged particles in the body fluids if an equipment failure caused the magnetic field to be shut off suddenly. An induced emf could cause these particles to flow, producing an electric current within the body. Suppose the largest surface of the body through which flux passes has an area of \(0.032 \mathrm{m}^{2}\) and a normal that is parallel to a magnetic field of \(1.5 \mathrm{T}\). Determine the smallest time period during which the field can be allowed to vanish if the magnitude of the average induced emf is to be kept less than \(0.010 \mathrm{V}\).

The rechargeable batteries for a laptop computer need a much smaller voltage than what a wall socket provides. Therefore, a transformer is plugged into the wall socket and produces the necessary voltage for charging the batteries. The batteries are rated at \(9.0 \mathrm{V},\) and a current of \(225 \mathrm{mA}\) is used to charge them. The wall socket provides a voltage of \(120 \mathrm{V}\). (a) Determine the turns ratio of the transformer. (b) What is the current coming from the wall socket? (c) Find the average power delivered by the wall socket and the average power sent to the batteries.

In 1996, NASA performed an experiment called the Tethered Satellite experiment. In this experiment a \(2.0 \times 10^{4}-\mathrm{m}\) length of wire was let out by the space shuttle Atlantis to generate a motional emf. The shuttle had an orbital speed of \(7.6 \times 10^{3} \mathrm{m} / \mathrm{s},\) and the magnitude of the earth's magnetic field at the location of the wire was \(5.1 \times 10^{-5}\) T. If the wire had moved perpendicular to the earth's magnetic field, what would have been the motional emf generated between the ends of the wire?

A standard door into a house rotates about a vertical axis through one side, as defined by the door's hinges. A uniform magnetic field is parallel to the ground and perpendicular to this axis. Through what angle must the door rotate so that the magnetic flux that passes through it decreases from its maximum value to one-third of its maximum value?

Near San Francisco, where the vertically downward component of the earth's magnetic field is \(4.8 \times 10^{-5} \mathrm{T}, \mathrm{a}\) car is traveling forward at \(25 \mathrm{m} / \mathrm{s}\) The width of the car is \(2.0 \mathrm{m}\). (a) Find the emf induced between the two sides of the car. (b) Which side of the car is positive - the driver's side or the passenger's side?

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