In the early part of the 19th century electricity and magnetism were seen as two discrete areas of physics. With the experimental work of Michael Faraday, and later the mathematical analysis of James Clerk Maxwell, these two areas of physics were unified by the theory of electromagnetism.
What was discovered is that moving charges, in magnetic fields will experience a forces. In essence, this is due to the fact that moving charges generate magnetic fields which thereby interact with the magnetic fields that they are in.
This is the principle behind electric motors
What was also discovered was that electric charges experiencing changing magnetic fields, or changes of flux, would experience a force and thus an EMF generated.
This underpins the concept of electrical generation.
The following lessons examines the key physical principles and mathematical models that underpin these behaviours.
What was discovered is that moving charges, in magnetic fields will experience a forces. In essence, this is due to the fact that moving charges generate magnetic fields which thereby interact with the magnetic fields that they are in.
This is the principle behind electric motors
What was also discovered was that electric charges experiencing changing magnetic fields, or changes of flux, would experience a force and thus an EMF generated.
This underpins the concept of electrical generation.
The following lessons examines the key physical principles and mathematical models that underpin these behaviours.
Hand Rules Explained
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Before we continue it's an important to learn the hand rules that are used in studying electromagnetism.
Hand rules are 'tool's used to establish the correct relationship between the vectors of electrical current, force, EMF and magnetic field. There are two in predominant use the first is Fleming's hand rules the second is the Palm rule. This video discusses both. Both are equally valid, however it is best to consistently use one or the other. |
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Moving Charge behaviour in an Electric field
We know that charges experience forces in electric fields. So how do these fields affect the charge whilst it is in motion?
This video, using the example of a crooks tube, examines the mathematical principles behind the force on moving charges within an Electric field.
Interactive
This is a simulation of a charged particle being shot into a uniform electric field. By Tom Walsh
One way to use this is to change one variable at a time and
This is a simulation of a charged particle being shot into a uniform electric field. By Tom Walsh
One way to use this is to change one variable at a time and
- predict the charge behaviour
- Run the simulation
- Explain the results in terms of the concepts here, as well as other physics principles
Sample Problem
We are now ready to try a sample problem
Below is a sample problem with a video that explain how to solve it. It is suggested you try the problem beforehand, as this actually aids understanding, even if you are unsure if you are correct.
We are now ready to try a sample problem
Below is a sample problem with a video that explain how to solve it. It is suggested you try the problem beforehand, as this actually aids understanding, even if you are unsure if you are correct.
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More problems to try
- A positive test charge of 6.5 x 10-6 C experiences a force of 4.5 x 10-5 N. What is the magnitude of the electric field intensity? (6.9 NC-1)
- An electric field of intensity 150 V/m exists between two plates separated by 4.0 m. What is the potential difference between the plates? (600V)
- A potential difference of 0.90 V exists from one side to the other of a cell membrane that is 5.0 x 10-9 m thick. What is the electric field across the membrane? (1.8 x 108 NC-1)
