AQA · A-Level · Physics
Course version: 7408 · Version from Sept 2016
Use as magnetic field sensor to monitor attitude.
Full specification wording
Hall effect sensor (A-level only): Use as magnetic field sensor to monitor attitude.
A Hall effect sensor measures magnetic flux density by producing a transverse voltage when a current-carrying conductor is placed in a magnetic field.
Checked against the AQA 7408 specification (opens in a new tab) on .
- Point 1 of 2
- 4 key terms
Study notes
From the checked teaching notes for this specification point.
The idea
A Hall effect sensor measures magnetic flux density by producing a transverse voltage when a current-carrying conductor is placed in a magnetic field. The Hall voltage is given by V_H = B I / (n t e), where B is magnetic flux density, I is current, n is charge carrier density, t is thickness and e is elementary charge. In attitude monitoring, sensors measure components of Earth's magnetic field along three orthogonal axes. From these components, the orientation of a vehicle or device relative to the magnetic field can be determined. The sensor must be calibrated and may need temperature compensation. It is used in spacecraft, drones and smartphones for heading and attitude estimation.
What earns the marks
- The Hall effect produces a transverse voltage across a current-carrying conductor in a magnetic field.
- The Hall voltage depends on magnetic flux density, current, charge carrier density, thickness and elementary charge.
- A Hall sensor can measure the component of magnetic field perpendicular to the sensor plane.
- Three orthogonal Hall sensors can determine the full magnetic field vector for attitude monitoring.
- Calibration and compensation are needed to account for temperature, offset and interference.
- Attitude is inferred from the measured magnetic field components relative to a reference frame.
Common mistakes and how to put them right
Confusing Hall voltage with induced e.m.f. from electromagnetic induction.
Put it right: The Hall effect is a steady transverse voltage due to charge separation in a magnetic field.
Forgetting that the Hall voltage depends on the angle between the magnetic field and the sensor plane.
Put it right: Only the perpendicular component is measured.
Assuming a single Hall sensor can determine full 3D attitude.
Put it right: Three orthogonal sensors or a combination with other sensors is needed.
Exam tips
- State the Hall voltage equation and define each symbol with correct units.
- Explain how three orthogonal sensors give the magnetic field vector components for attitude determination.
- Discuss practical limitations such as temperature drift, calibration and magnetic interference.
Try the lesson
The start of the Hall effect sensor (A-level only): Use as magnetic field sensor to monitor attitude. lesson, made from checked teaching notes for this specification point.
Have a go first
A Hall effect sensor is used as a magnetic field sensor to monitor the attitude of a satellite. What does the sensor produce that indicates the magnetic field it experiences?
Listen
A Hall effect sensor measures magnetic flux density by producing a transverse voltage when a current-carrying conductor is placed in a magnetic field. The Hall voltage is given by V_H = B I / (n t e), where B is magnetic flux density, I is current, n is charge carrier density, t is thickness and e is elementary charge. In attitude monitoring, sensors measure components of Earth's magnetic field along three orthogonal axes. From these components, the orientation of a vehicle or device relative to the magnetic field can be determined. The sensor must be calibrated and may need temperature compensation. It is used in spacecraft, drones and smartphones for heading and attitude estimation. A strong answer earns marks for these points. The Hall effect produces a transverse voltage across a current-carrying conductor in a magnetic field. The Hall voltage depends on magnetic flux density, current, charge carrier density, thickness and elementary charge. A Hall sensor can measure the component of magnetic field perpendicular to the sensor plane. Three orthogonal Hall sensors can determine the full magnetic field vector for attitude monitoring. Exam tip: State the Hall voltage equation and define each symbol with correct units.
Key words
Say what each word means before you turn the card.
Hall effect
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Hall voltage
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Attitude monitoring
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Calibration and compensation
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See every definition
- Hall effect
- A steady transverse voltage is produced across a current-carrying conductor placed in a magnetic field due to charge separation.
- Hall voltage
- Given by V_H = B I / (n t e), where B is magnetic flux density, I is current, n is charge carrier density, t is thickness and e is elementary charge.
- Attitude monitoring
- Sensors measure components of Earth's magnetic field along three orthogonal axes, from which the orientation of a vehicle or device relative to the magnetic field can be determined.
- Calibration and compensation
- The sensor must be calibrated and may need temperature compensation to account for temperature, offset and interference.
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