Hall voltage is directly proportional to several factors in the context of the **Hall effect**, which occurs when a current-carrying conductor is placed in a magnetic field. The Hall voltage, which is the voltage that develops across the conductor in the direction perpendicular to both the current and the magnetic field, is directly proportional to the following:
### 1. **Magnetic Field Strength (B)**
The Hall voltage (\(V_H\)) increases as the strength of the magnetic field increases. The relationship is linear, meaning that if the magnetic field is doubled, the Hall voltage also doubles. This is because the magnetic field exerts a greater force on the moving charge carriers (such as electrons), which results in a higher accumulation of charge on one side of the conductor, increasing the Hall voltage.
### 2. **Current (I)**
The Hall voltage is also directly proportional to the current flowing through the conductor. As the current increases, the number of charge carriers moving through the conductor increases, leading to a stronger buildup of charge on the sides, thereby increasing the Hall voltage. If you double the current, the Hall voltage doubles as well.
### 3. **Carrier Concentration (n)**
The Hall voltage depends on the concentration of charge carriers in the material (usually electrons in metals or semiconductors). The more charge carriers present, the less the effect of the magnetic field on individual charge carriers, leading to a smaller Hall voltage. Therefore, the Hall voltage is inversely proportional to the carrier concentration. This means that materials with lower carrier concentrations will exhibit a higher Hall voltage for the same magnetic field and current.
### 4. **Width (w) of the Conductor**
The Hall voltage is inversely proportional to the width of the conductor. In a wider conductor, the charge carriers have more space to move, which reduces the build-up of charge on the sides and, consequently, the Hall voltage. So, a wider conductor will produce a smaller Hall voltage for the same current and magnetic field.
### Summary of the relationship:
The Hall voltage \( V_H \) is given by the formula:
\[
V_H = \frac{IB}{nqwd}
\]
Where:
- \( I \) = current through the conductor
- \( B \) = magnetic field strength
- \( n \) = charge carrier concentration
- \( q \) = charge of the carrier
- \( w \) = width of the conductor
- \( d \) = thickness of the conductor
Thus, Hall voltage is **directly proportional to**:
- The magnetic field strength (B)
- The current (I)
And **inversely proportional to**:
- The charge carrier concentration (n)
- The width (w) of the conductor
This proportionality makes the Hall voltage a useful tool for measuring magnetic fields and determining the properties of materials, such as carrier concentration.