Hall Effect Questions

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Very Short Answers Questions [1 Mark Questions]

Ques. Who discovered the Hall effect?

Ans. When a solid material conducts an electric current and is put in a magnetic field that is perpendicular to the current, a transverse electric field develops. This phenomenon is known as the Hall effect. Edwin Herbert Hall, a physicist from the United States, discovered this phenomenon in 1879.

Ques. The Hall coefficient is _____ if the number of positive charges is more than the negative charges.

1. Negative
2. Positive
3. Zero
4. Neither negative nor positive

Ans. The correct answer is b. Positive

Explanation: The Hall coefficient is positive if the number of positive charges exceeds the number of negative charges.

Ques. Can the magnetic field be calculated with a Hall probe using the Hall effect?

1. True
2. False

Ans. The correct answer is a. True

Explanation: Using the Hall effect, a magnetic field may be determined with a Hall probe.

Ques. Define proximity sensor.

Ans. A proximity sensor is a sensor that can detect the presence of nearby objects without making physical contact.

Ques. The Hall effect is used in phase angle measurement.

1. True
2. False

Ans. The correct answer is a. True

Explanation: Yes, the Hall effect can be used to calculate phase angles. It is also used to determine the speed of the wheel.

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Short Answers Questions [2 Marks Questions]

Ques. What is the Hall effect?

Ans. Hall effect is the formation of a potential difference, also known as Hall voltage, across the surface of an electrical conductor when the current in the conductor is transverse to the magnetic field applied to the conductor and the magnetic field is perpendicular to the present current.

Ques. Can the Hall coefficient be zero?

Ans. The Hall coefficient is affected by the hole/electron concentration as well as carrier mobility. The gap between the conduction and valence bands is quite large in an insulator. Because conductivity is zero in insulators, mobility is close to zero as well. As a result, in the case of an insulator, the Hall effect is zero.

Ques. What is a Hall effect sensor?

Ans. A Hall effect sensor is an electronic device that detects the Hall effect and converts its findings into electronic data, which may then be used to either switch a circuit on and off, provide a measurement of a fluctuating magnetic field, be processed by an integrated computer, or be shown on an interface.

Ques. What is the Hall field?

Ans. Due to the Hall Effect, an electric field develops over the width of a conductor in the presence of an external magnetic field, while an electric current flows under its influence is known as the Hall field.

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Long Answers Questions [3 Marks Questions]

Ques. What is a quantum hall effect?

Ans. The quantum Hall effect is the quantum mechanical equivalent of the Hall effect. 

• This is observed in a two-dimensional system of electrons subjected to low temperatures and high magnetic fields, and these systems do not exist naturally, but rather by the use of modern technology and manufacturing procedures created in semiconductor devices. 
• The quantum Hall effect, which is the quantization of the Hall resistance, may be detected in the presence of a strong magnetic field and a low temperature.

Ques. What is the Hall effect in semiconductors?

Ans. If a current-carrying semiconductor is placed in a magnetic field, the carriers of charge in the semiconductor will experience a force that is perpendicular to both the current and the magnetic field. 

• Electrons in a semiconductor move in a closed trajectory, but under strong magnetic fields and at normal temperatures, this mobility is broken by collisions. 
• Because of this phenomenon, the concentration and mobility of the charge carriers present in a semiconductor, which are electrons and holes, will vary. 
• The Hall effect may be used to identify whether a semiconductor is p-type or n-type; if the produced voltage is positive, the semiconductor is p-type; if the produced voltage is negative, the semiconductor is n-type.

Ques. What are the advantages of using Hall Effect Switches?

Ans. The following are the advantages of using Hall effect switches

• Hall effect switches are capable of performing a variety of sensor functions, including location sensing, proximity detection, directional movement, speed tracking, and current sensing. This function is extremely useful in the electrical and automotive sectors.
• Hall effect switches are usually unaffected by environmental factors such as dust, humidity, and vibrations. Because they have a continuous flow of electrical current, their properties stay consistent throughout time. As a result, these switches are extremely resistant to wear, keeping their quality and enabling indefinite usage.
• The output errors of standard Hall effect switches can be as low as 1%. Although a well-designed resistive current-sense circuit may outperform this, a 1% error would be sufficient for cases where these switches are suitable. Furthermore, they may be programmed to activate the switch at specific magnetic fields.

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Very Long Answers Questions [5 Marks Questions]

Ques. What are the applications of the Hall Effect? 

Ans. The following are the applications of the Hall effect

• Semiconductor Hall devices: Hall devices are used in circuits to detect current and potential. This is beneficial in a variety of applications, including integrated circuit design and testing. High-side and low-side Hall devices are common implementations.
• Hall Effect sensors: These are small solid-state semiconductor devices used to monitor magnetic fields such as those created by the Earth's magnetic field, as well as sensing for cars, airplanes, and electrical equipment. Hall sensors are also used in small products such as microwave ovens, microwave bread toasters, and cordless vacuum cleaners as an alternative to reed switches.
• Magnetoresistivity and Magnetoelectric effect: Electrons in a metallic conductor are free to move from one place to another. Because of its mobility, the conductor can be polarised by the magnetic field. The flow of electrons generates a change in conductor resistance, which may be measured using a Hall voltmeter. The direction and strength of the electric field influence the resistance change. The conductor's resistivity and magnitude of resistance change with the direction and strength of the magnetic field in this phenomenon.
• Electro-conductive materials for electromagnetic measurement: The Hall Effect's ability to measure the electric field allows it to be used to determine the resistivity and surface conductivity of non-metallic materials.

Ques. Calculate the width of the conductor slab having the concentration of the carrier is 1020 if the Hall voltage of 0.8 V develops across the slab when a magnetic field of 6 A/m is applied and the current flowing through the conductor is 2 A. 

Ans. Given

• Applied magnetic field, B = 6 A/m
• Current flowing through the conductor, I = 2 A
• Hall voltage develops across the slab, V_h = 0.8 V
• Carrier concentration, n_e = 10²⁰

The formula for the Hall voltage is given by

V_h = BI / need

Where

• B is the magnetic field
• d is the width of the cross-section of the conductor
• V_h is the Hall voltage
• I is the current
• n_e is the charge carrier density
• e is the charge of an electron

Therefore, the width of the conductor slab is given by

d = BI / n_eeV_h

⇒ d = (6 x 2) / (10²⁰ x 1.6 x 10^-19 x 0.8)

⇒ d = 12/12.8 = 0.94 m

Ques. Calculate the Hall voltage when the magnetic field is 6 A/m, the current is 3 A, the width is 4 m, and the concentration of carrier is 10²¹

Ans. Given

• Magnetic field, B = 6 A/m
• Current, I = 3 A
• Width, d = 4 m
• Carrier concentration, n_e = 10²¹

The formula for the Hall voltage is given by

V_h = - BI / n_eed

⇒ V_h = (6 x 3) / (10²¹ x 1.6 x 10^-19 x 4)

⇒ V_h = 18/640 = 0.028 V

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