Hall Effect, reversing magnetic fields

Expert SummarizerIn summary, the conversation discusses the Hall effect and its application to a p-type semiconductor bar with measurements taken at different magnetic field directions. The Hall voltage, which changes sign when the field direction is reversed, is used to calculate the hole concentration and mobility using the given equations. The expert clarifies the concept of the Hall effect and offers assistance with any further questions.
  • #1
Krogy
3
0

Homework Statement



Hall measurements are made on a p-type semiconductor bar (X) μm wide and (Y) μm thick. The Hall contacts A and B are displaced (Z) μm with respect to each other in the direction of current flow of (I) mA. The voltage between A and B with a magnetic field of 10 kG (1kG = 10^-5 Wb/cm2) pointing out of the plane of the sample is 3.2 mV. When the magnetic field direction is reversed the voltage changes to -2.8 mV. What is the hole concentration and mobility?


Homework Equations



w*Ey =[Ix*Bz]/[q*p*t] (p-type)
p =[Ix*Bz]/[w*Ey*q*t]

The Attempt at a Solution



What is killing me here is the magnetic field reversal. How does reversing the magnetic field allow us to get the true hall voltage? I don't understand this concept, shouldn't the hall voltage just be opposite when reverse. Doesn't the holes and electrons just switch polarity?
 
Physics news on Phys.org
  • #2


Thank you for your post. The phenomenon you are describing is known as the Hall effect, which is a fundamental principle in solid state physics. When a current is applied to a semiconductor, it creates a magnetic field that interacts with the applied magnetic field. This interaction results in a voltage difference between the two Hall contacts, which is known as the Hall voltage.

In your case, the Hall voltage changes sign when the direction of the applied magnetic field is reversed. This is because the direction of the Lorentz force, which is responsible for the Hall effect, also changes. This change in direction results in a change in the polarity of the Hall voltage.

To calculate the hole concentration and mobility, you can use the equations you have provided in your post. The key parameters you will need are the width and thickness of the semiconductor bar, the displacement between the two Hall contacts, the magnitude of the applied magnetic field, and the Hall voltage for both directions of the magnetic field.

I hope this helps to clarify the concept of the Hall effect for you. If you have any further questions, please do not hesitate to ask.
 

1. What is the Hall Effect?

The Hall Effect is a phenomenon in physics where an electric current is deflected when it passes through a magnetic field and a voltage is generated perpendicular to the current and magnetic field.

2. How does the Hall Effect work?

When a current-carrying conductor is placed in a magnetic field, the electrons in the conductor experience a force perpendicular to both the current and the magnetic field. This causes the electrons to accumulate on one side of the conductor, creating a voltage difference between the two sides.

3. What is the application of the Hall Effect?

The Hall Effect has a variety of applications, including measuring magnetic fields, determining the type of charge carriers in a material, and creating sensors for current, position, and speed measurements.

4. Can the Hall Effect be used to reverse a magnetic field?

No, the Hall Effect does not have the ability to reverse a magnetic field. However, it can be used to measure changes in magnetic fields, including changes in direction or strength.

5. How is the Hall Effect used in electronics?

The Hall Effect is commonly used in electronic devices such as sensors, switches, and motor controllers. It can also be used to control the flow of current in electronic circuits by using a magnetic field to deflect the path of the current.

Similar threads

  • Electromagnetism
Replies
7
Views
892
  • Advanced Physics Homework Help
Replies
2
Views
2K
  • Introductory Physics Homework Help
Replies
19
Views
2K
Replies
1
Views
656
  • Advanced Physics Homework Help
Replies
1
Views
2K
  • Electromagnetism
Replies
2
Views
1K
  • Advanced Physics Homework Help
Replies
1
Views
4K
  • Advanced Physics Homework Help
Replies
2
Views
1K
Replies
20
Views
3K
  • Advanced Physics Homework Help
Replies
2
Views
5K
Back
Top