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Course: High school physics - NGSS > Unit 2
Lesson 5: Electric and magnetic fieldsElectric and magnetic fields
Review your understanding of electric and magnetic fields in this free article aligned to NGSS standards.
Key terms
| Term | Meaning |
|---|---|
| Field | A field models what an object would experience related to a force at a given point in space. |
| Magnetic Field | A magnetic field is a field explaining the magnetic influence on an object in space. |
| Electric Field | A electric field is a field defined by the magnitude of the electric force at any given point in space. |
| Current | Current is the rate of charge moving past a region. |
Forces at a distance and fields
Forces at a distance, such as gravitational, electric, and magnetic forces, can be represented using vector fields. These fields describe a relationship a given object might experience to the forces at any point in space.
Fields are often represented in two dimensions using field lines. The density of these field lines indicates the strength of the field at a particular point - the more dense the lines, the stronger the field. The conventions for how to show gravitational, electric, and magnetic field lines are all slightly different to model the unique aspects of each force. Some common models are shown below.
Electric fields
Electric fields arise from electric charges and changing magnetic fields.
An electric charge, or a collection of charges, will have an associated electric field. Any charged object placed in this field will experience an electrostatic force as the field interacts with the charge of the object. Field lines represent the force a positively charged particle would experience if it were in the field at that point.
A changing magnetic field can also cause electric charges to move. This phenomenon is commonly used in electric generators to induce electric currents in wires. The induced current can be increased by causing larger changes in the magnetic field or by coiling the wire so that more wire is affected by the changing magnetic field.
Magnetic fields
Magnetic fields arise from permanent magnets and electric charges in motion.
Magnets can occur naturally (such as the Earth’s magnetic field), or they can be made by magnetizing ferromagnetic materials.
Magnetic fields ultimately are the result of the motion of charges. A typical representation of this can be seen in the figure below. We can see the magnetic field surrounding the straight wire as current is moving through it. We use this phenomenon to run motors and even to store information in computers.
The magnetic field around a current-carrying wire can be increased by coiling the wire or increasing the current running through it. In a magnetic field, the field lines represent the force the north side of a magnet might experience if it were in the field at that point.
Want to join the conversation?
Does the earth have a magnet inside?(9 votes)- earth as a whole is a magnet(7 votes)
- why do moving charges cause an magnetic field?(2 votes)
- beacause the electric and magnetic force are tightly related and form togheter the ELECTROMAGNETIC FORCE which is defined by Maxwell's equations, a set of 4 equations (not all developed by Maxwell), Faraday's Law, Ampere's Law (with Maxwell's additions), Gauss's Law (not the math one) and Gauss's Law for magnetism(5 votes)
how do Electric fields arise form changing magnetic fields ?(2 votes)
This is what I found in answer to your question!
Electric fields arise from electric charges and changing magnetic fields. Let me explain how this happens:
Electric Charges:
An electric charge, or a collection of charges, generates an electric field around it.
Any charged object placed in this field will experience an electrostatic force as the field interacts with the charge of the object.
Changing Magnetic Fields:
When a magnetic field changes over time (for example, due to the motion of a magnet or a current-carrying wire), it induces an electric field.
This phenomenon is described by Faraday’s law of electromagnetic induction.
The changing magnetic field creates a circulating electric field, which can lead to the flow of electric current in a conductor (such as a wire) if the circuit is closed.
Conversely, a changing electric field can also induce a magnetic field, as described by Ampère’s law.
Electromagnetic Waves:
When an electric field and an accompanying magnetic field propagate through space as a radiated wave, they form an electromagnetic wave.
These waves travel at the same speed as light and are generated not only from electric charges but also from changing magnetic fields.
Electromagnetic waves include radio waves, microwaves, visible light, and X-rays.
In summary, electric fields arise from both stationary electric charges and changing magnetic fields, and they play a crucial role in the behavior of electromagnetic waves.
Hope this helps!
Happy Learning!
Angelina(2 votes)
- What is Forces at a distance and fields(1 vote)
- Here is what I found to answer your question!
Forces at a distance refer to interactions between objects that do not require physical contact. Instead of direct contact, these forces create an area around an object called a field, which can affect other objects within that field.
Hope this helps!
Happy Learning!
Angelina(2 votes)
- Forces at a distance and fields?(1 vote)
- Here is what I found to answer your question!
Forces at a distance refer to interactions between objects that do not require physical contact. Instead of direct contact, these forces create an area around an object called a field, which can affect other objects within that field.
Hope this helps!
Happy Learning!
Angelina(1 vote)
- dose any other planets have a magnetic field.(1 vote)
In our solar system, jupiter, saturn, uranus and neptune have strong magnetic fields. As conductive materials in these planets generate electric currents through motion and convection(dynamo effect)(1 vote)
- How is the direction of the circular magnetic field caused by electric current through a wire determined?(0 votes)
- the direction of the magnetic field around a current-carrying wire is a consequence of the Biot-Savart law. You can visualize it with the help of the right-hand rule, as you grab the wire your thumb points up to the direction of current and your curled fingers show the direction of rotation of the magnetic field(1 vote)
- Does the earth have a magnet inside(0 votes)
