Last updated on Sunday, October 15th, 2023

Hall Effect is a phenomenon that occurs when a semiconductor material is placed in a uniform magnetic field. If the current is flowing along the x-direction, and the magnetic field is applied along the y-direction then a potential difference will generate along the z-direction inside the semiconductor. This potential difference is directly proportional to the applied magnetic field.

Hall Effect Introduction

To understand it we require some supporting physical concepts (SPCs). These are;

1. Lorentz’s Force
2. n-type or p-type semiconductor working

The Hall Effect Principle has been introduced in 1879 by an American physicist Edwin H. Hall. There are many applications based on this principle of Hall Sensor to Hall Switch.

The basics of the Hall effect experiment are already explained and discussed with viva questions. So, you can watch and learn about it at this link.

CLICK HERE: Hall Effect Experiment, how to observe Hall Voltage- First Part.

Here, we can conclude this;

1. Hall Voltage is directly proportional to Electric Current, and
2. Hall Voltage is directly proportional to the applied magnetic field.

Recommended reading: Hall effect Experiments theory and Viva questions

Hall Effect Experiment Procedure:

Zero Calibration:

Zero calibration must be done before the experiment. Before placing the Hall probe in a magnetic field, pass some current through it and note the corresponding value of the Hall voltage. Adjust this value to zero. This is zero calibration of Hall voltage.

Connections:

Now place the hall probe in a magnetic field and connect four wires in such a way that the current passes through the probe lengthwise and voltage is developed width-wise.

Calibration of magnetic field:

After placing the hall probe in a magnetic field and completing connections give a certain amount of current to the hall probe. We noted that some hall voltage is developed. Now increase the value of the magnetic field and again noted the corresponding readings of hall voltage. Repeat this process for different values of the magnetic field by using the formula;

B = V_Hb/ R_HI           ————–(1)

Where, V_H  = Hall Voltage

R_H  = Hall Coefficient.

Determination of RH values of other samples :

Now, after determining the value of current through the probe for a particular magnetic field i.e. for different values of other probe currents. Now change the magnetic field i.e. change the current through the magnet and repeat the same process. We take observations for different values of the magnetic field and determine the value of the hall coefficient by using

R_H  =  V_Hb/ BI

The quantity E_H / JB is the hall electric field per unit current density per unit magnetic field is called Hall Coefficient and is denoted by R_H.

Thus,  R_H  = 1/ne

Observations :

Calibration of Magnetic Field

The thickness of semiconductor material=0.5 mm

Sample no. of probe = 2091 (p-type) [May vary from lab to lab]

Current through the probe, I_H = 0.53 mA

Hall coefficient of probe (Ge), R_H = 19.07 × 10^-3 m³/C

2. Current through magnet=0.3A

Magnetic field, B= 0.061837718T

Average value of R_H = 0.021109699 m³/C

3. Current through magnet = 0.4 A

Magnetic field, B = 0.086572805 T

Average value of RH = 0.02564903 m3/C

4. Current through magnet = 0.5 A

Magnetic field, B = 0.11625491 T

Average value of R_H = 0.02403 m³/C

Mean R_H values = (0.021109699  + 0.02564903  + 0.024033)/3 = 0.025530872 m³/C

PRECAUTIONS :

1. Hall voltage should be measured very carefully and accurately.
2. The current through probe should not exceed a certain minimum value.
3. The digital voltmeter should be handled carefully.
4. The distance between pole pieces of the electromagnet should not be changed during the whole experiment.

Applications of the Hall Effect Principle

Hall Effect Principle is used in: –

• Magnetic field sensing equipment.
• Multiplier applications to provide actual multiplications.
• Hall Effect Tong Tester for measurement of direct current.
• Phase angle measurement. For example – in measuring the angular position of the crankshaft to accurately align with the firing angle of the spark plugs.
• Linear or Angular displacement transducers. For example – to identify the position of the car seats and seat belts and act as an interlock for air-bag control.
• Proximity detectors.
• Hall Effect sensors and probes.
• For detecting wheel speed and accordingly assist anti-lock braking system (ABS).
• Because of its simplicity, low cost, and fast turnaround time, it is an indispensable characterization technique in the semiconductor industry and in research laboratories.

FAQ Hall Effect

For related questions check the earlier Hall Effect Post.

CREDITS: Thanks to Priyanka Verma, and the team for the observation, graph, precautions, and applications.

NOTE: Observation data is shared to learn the calculations at different currents, please avoid copy-paste of observation table.