Hall Effect
The Hall Effect is a phenomenon that occurs when a current-carrying conductor or semiconductor is placed in a magnetic field perpendicular to the current. The magnetic field exerts a force on the moving charges, causing them to accumulate on one side of the conductor. This creates a voltage difference (Hall voltage) across the conductor that is perpendicular to both the current and magnetic field.
What is the Hall Effect?
Key Concept
When a current-carrying conductor or semiconductor is placed in a magnetic field perpendicular to the current, the moving charges (usually electrons) are deflected to one side by the magnetic force. This causes a buildup of charge on one side, creating an electric potential difference (Hall voltage) across the conductor. The Hall voltage is always perpendicular to both the current and the magnetic field.
Physical Meaning
The Hall Effect allows us to determine the type of charge carrier (positive or negative), their density, and the strength of the magnetic field. The sign of the Hall voltage tells us whether the charge carriers are electrons (negative) or holes (positive).
Applications of the Hall Effect
- Measuring magnetic field strength
- Determining charge carrier type and density in semiconductors
- Position and speed sensors (Hall sensors)
- Non-contact current sensing
Example: Understanding the Hall Effect
- A thin strip of metal carries a current to the right and is placed in a magnetic field pointing into the page. What happens to the electrons in the strip?
- The electrons are deflected by the magnetic field toward one side of the strip, causing that side to become negatively charged and the opposite side to become positively charged.
- This separation of charge creates a measurable electric potential difference (Hall voltage) across the strip, perpendicular to both the current and the magnetic field.
Key Takeaways
- The Hall Effect produces a voltage perpendicular to both current and magnetic field.
- The sign of the Hall voltage reveals the type of charge carrier.
- The Hall Effect is widely used in sensors and semiconductor analysis.