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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Charge behaviour in an Magnetic field
Interactive
Let's start by first examing this simulation (By Tom Walsh) of a charged particle being shot into a magnetic field.
Let's start by first examing this simulation (By Tom Walsh) of a charged particle being shot into a magnetic field.
- Set the variables and fire a charge in the field
What do you observe?
You should notice it travels in a circular path.
The reason is that since a moving charge generates a magnetic field, this field interacts with the external field it is entering, resulting in a force.
This force is always perpendicular to the velocity of the charge. This causes the charge to undergo circular motion.
Watch the video as this is further elaborated on this concept.
The reason is that since a moving charge generates a magnetic field, this field interacts with the external field it is entering, resulting in a force.
This force is always perpendicular to the velocity of the charge. This causes the charge to undergo circular motion.
Watch the video as this is further elaborated on this concept.
Check your understanding
Interactive
Let's now revisit the interactive above. The instructions below allow you to consolidate and test your understanding.
Let's now revisit the interactive above. The instructions below allow you to consolidate and test your understanding.
- Set the variables to some value
- Fire a trace
- Change ONE variable, keeping all others constant and PREDICT what will happen
- Fire the trace to test your prediction.
Can you explain the trace? - Repeat for another variable
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
- An unknown particle having a mass of 2.2 x 10-27 kg and a charge of 3.3 x 10–19 C passes through a magnetic field of 5.4 x 10-1 T. The velocity of the particle is 6.4 x 103 m/s. What is the radius of its path? (7.9 x 105 m)
- A particle with a mass of 3.8 x 10-27 kg and a charge of 6.2 x 10–19 C crosses a magnetic field that measures 2.7 x 10-2 T. The particle assumes a circular path with a radius of 1.5 x 10-1 m. At what speed is the particle moving? (660, 790 m/s)
- A particle passing through a magnetic field has a mass of 6.3 x 10–27 kg and is moving at 3.9 x 104 m/s. The charge on the particle is 2.4 x 10-18 C and the radius of its circular path through the field is 4.4 x 10-2 m. What is the strength of the magnetic field? (0.00233 T)
- A particle with a mass of 3.34 x 10-27 kg and a charge of 1.2 x 10-19 C passes through a magnetic field of 3.4 x 10-3 T. This causes the nucleus to assume a circular path with a radius of 0.065 m. What is its velocity? (4940.1 m/s)
