Summary of Magnetic Field: Coil

Goals

1. Understand the basic principles of the magnetic field created by coils.

2. Calculate the magnetic field in various coil configurations.

3. Apply what you've learned to solve real-world problems.

4. Get familiar with the tools and techniques used to measure magnetic fields.

5. Work collaboratively while conducting experiments.

Contextualization

The magnetic field created by a coil is a key concept in physics that also has many practical applications. Think of a train gliding over frictionless tracks or an electric car powered by efficient motors. These advancements rely on our understanding and manipulation of magnetic fields. In this lesson, we will investigate how coils generate magnetic fields and how to calculate their strength, equipping students with the knowledge to grasp the technologies shaping our world today.

Subject Relevance

To Remember!

Definition of Magnetic Field

A magnetic field is the area surrounding a magnet or electric current where magnetic forces can be felt. It is a vector quantity, meaning it has both direction and magnitude, and is illustrated by field lines that radiate from the north pole and converge at the south pole of a magnet.

• Magnetic fields are produced by magnets and electric currents.

• The strength of a magnetic field is measured in teslas (T).

• Magnetic field lines do not cross and are denser in stronger fields.

Fundamental Principles of the Magnetic Field Generated by Coils

When an electric current flows through a coil, it creates a magnetic field around it. The strength of this field can be enhanced by increasing either the number of coils or the current flowing through. The direction of the magnetic field follows the right-hand rule: if you curl the fingers of your right hand in the direction of the current, your thumb will point in the direction of the magnetic field.

• The magnetic field produced by a coil is directly related to the number of turns and the current.

• You can use the right-hand rule to determine the direction of the magnetic field.

• Inserting an iron core inside the coil can significantly boost the magnetic field strength.

Formula for Calculating the Magnetic Field in Coils

You can calculate the magnetic field in a coil using the formula B = (μ₀ * N * I) / L, where B is the magnetic field, μ₀ is the permeability of free space, N is the number of turns, I is the current, and L is the length of the coil. This formula enables you to determine the strength of the magnetic field in various coil setups.

• B = (μ₀ * N * I) / L is the fundamental formula for calculating magnetic fields in coils.

• μ₀ (permeability of free space) is a universal constant valued at approximately 4π x 10^-7 T*m/A.

• Increasing the number of turns or the current produces a stronger magnetic field.

Practical Applications

• MRI machines in hospitals leverage superconducting coils to create strong and precise magnetic fields crucial for capturing detailed images of the human body.

• Maglev trains utilize magnetic fields created by coils to levitate and propel the trains, eliminating friction and enabling high speeds with energy efficiency.

• Electric motors in everyday devices such as fans, computers, and electric vehicles rely on the principles of magnetic fields generated by coils to convert electrical energy into mechanical motion.

Key Terms

• Magnetic Field: The area surrounding an electric current or magnet where magnetic forces are exerted.

• Coil: An electrical component comprised of wire wound into turns, used for generating magnetic fields or inducing current.

• Electric Current: The flow of electric charges through a conductor, measured in amperes (A).

• Permeability of Free Space (μ₀): A physical constant that describes how well free space can support the formation of a magnetic field, approximately valued at 4π x 10^-7 T*m/A.

Questions for Reflections

• How might magnetic levitation technology transform urban and intercity transportation in the years to come?

• What are the main hurdles in creating superconducting coils for use in MRI machines?

• In what ways can industries benefit from investing in technologies that harness magnetic fields produced by coils?

Practical Challenge: Measuring the Magnetic Field of a Coil

Construct a simple coil and use a smartphone app to measure the magnetic field it generates, comparing the actual results with theoretical calculations.

Instructions

• Wrap copper wire around a nail to make a coil with several turns.

• Connect the wire ends to a power source, like batteries or a DC source, to create an electric current in the coil.

• Use a smartphone app that measures magnetic fields to capture the magnetic field strength at various points around the coil.

• Keep track of the measured values and compare them with the theoretical values calculated using the formula B = (μ₀ * N * I) / L.

• Discuss possible sources of experimental error and ways to enhance measurement accuracy.