Flemings Left Hand Rule and Right Hand Rule

Edited By Team Careers360 | Updated on Jul 02, 2025 04:29 PM IST

Electromagnetic induction happens because of Fleming’s Left hand rule and through Fleming’s right hand rule. John Ambrose Fleming was the one who came up with the idea of right hand thumb rule and left hand thumb rule. These simple rules give us a sense how electricity is generated or how forces act on current carrying wires in motors and generators. These rules make it easy to use directions of your thumb, your forefinger, and your middle finger to tell the direction of a force, current, or motion in electromagnetic systems.

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This Story also Contains

Fleming Left-Hand Thumb Rule
How to Apply Fleming's Left-Hand Rule?
Fleming Right Hand Rule
How to Apply Fleming's Right-Hand Rule?

Flemings Left Hand Rule and Right Hand Rule

Fleming Left-Hand Thumb Rule

Fleming's Left-Hand Thumb Rule is used to determine the force experienced by a current-carrying conductor when placed in a magnetic field. It is majorly used in understanding the working principle of electric motors.

On the thumb, forefinger, and middle finger, a left hand can be used to denote three mutually orthogonal axes. When the thumb, center finger, and forefinger of the left hand are arranged at right angles to one another, the thumb points in the direction of magnetic force, the center finger points in the direction of current, and the forefinger points in the direction of a magnetic field.

How to Apply Fleming's Left-Hand Rule?

Stretch the thumb, middle finger, and index finger of the left hand to form a 90-degree angle (perpendicular to each other), as shown in the figure:

Then,

Forefinger will represents the direction of the magnetic field (B), from north to south.
Middle finger will represents the direction of the current (I), from positive to negative.
Thumb will indicates the direction of the force (F) or motion of the conductor.

Flemings left hand rule diagram

Fleming's Left-Hand Rule in Electric Motors

When a moving conductor is placed inside a magnetic field, a current is induced in it, according to Faraday's law of electromagnetic induction.

There will be a link between the direction of applied force, magnetic field, and current if the conductor is forcefully moved inside the magnetic field.
It is mostly utilized in the operation of electric motors.
The rule's principal goal is to determine the direction of motion in an electric motor.
The direction of motion in an electric motor is determined by the popular Fleming's left-hand rule, which is based on Faraday's law of electromagnetic induction.

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Application of flemings left hand rule

1. We can identify the direction of force exerted on the proton using Fleming's left-hand rule.

Because the proton is going towards the east, the current is also moving towards the east. The force is directed towards the north since the magnetic field is acting downwards. As a result, we can say the force is acting northward.

2. We may identify the direction of the magnetic field acting on the electron using Fleming's left-hand rule. An electron has a negative charge, as we all know. The current runs in the opposite direction, down, when an electron moves upward. The force operating on the electron is thought to be in the direction of the south. As a result, the magnetic field is oriented towards the east.

Fleming Right Hand Rule

Fleming right hand rule is used to determine the direction of induced current when a conductor moves in a magnetic field. It is based on Faraday's Law of Electromagnetic Induction and is majorly applied in generators.

How to Apply Fleming's Right-Hand Rule?

Stretch out your thumb, forefinger, and middle finger of your right hand such that they are perpendicular to each other as demonstrated in the following figure:

Fleming right hand rule diagram

Then,

Thumb: It moves in the same direction as the conductor.

Forefinger: Represents the direction of the magnetic field (BBB), from north to south.

Middle finger: Indicates the direction of the induced current (III).

Applications of fleming's right hand rule

The direction of induced current within an electric generator is determined by Fleming's right hand rule.
This rule is used in dynamos used in bicycles, or similar, in which the motion is converted into electrical energy by means of their electric current.
Fleming's Right Hand Rule is used by devices such as wind turbines and hydroelectric generators to figure out how to convert mechanical energy (say wind movement, or water movement) into electricity through electro magnetic induction.
This rule is the basis of operation of magnetic sensors used in automotive and industrial applications and determine induced current.

Frequently Asked Questions (FAQs)

1. What is difference between Fleming left hand rule and right hand rule?

Fleming's left-hand rule gives the direction of magnetic force acting on a conductor whereas, Fleming's right-hand rule gives us the direction of induced current.

2. What does Fleming's left hand rule explain?

Fleming's left- hand rule explains that, if we stretch the thumb, middle finger and the index finger of the left hand in such a way that they make an angle of 90 degrees (Perpendicular to each other) and the conductor placed in the magnetic field experiences Magnetic force.

3. What is Fleming's right hand rule called?

Fleming's right hand is also known as dynamo rule. It gives the direction of induced current produced in a straight conductor moving in a magnetic filed.

4. When it comes to coils, what is the left-hand rule?

The left-hand rule of Fleming aids with movement prediction. A current-carrying coil of wire twists when it is put in a magnetic field. The motor effect is what this is known as.

5. What is the other name for the thumb rule on the right hand?

With the use of the Right Hand Thumb Rule, the direction of magnetic field lines produced by current flow can be hypothetically calculated. Clasp Rule is another term for right hand thumb rule.

6. What circumstances influence Fleming's rule of the left hand?

The force is greatest when the current direction is 90 degrees from the magnetic field direction for any given combination of current and magnetic field strength. If the current and magnetic field are parallel to one another, there is no motor effect force.

7. Can Fleming's hand rules be used to explain the Hall effect?

Yes, Fleming's Left Hand Rule can help explain the Hall effect. When a current-carrying conductor is placed in a magnetic field, the charge carriers experience a force perpendicular to both the current and the field. This force causes a separation of charges, creating a potential difference across the conductor. The direction of this Hall voltage can be determined using the Left Hand Rule.

8. Can Fleming's Left Hand Rule be used to explain the force between two parallel current-carrying wires?

Yes, Fleming's Left Hand Rule can explain the force between parallel current-carrying wires. Each wire creates a magnetic field around it. The current in one wire experiences a force due to the magnetic field of the other wire. By applying the Left Hand Rule to each wire separately, you can determine that parallel currents attract, while antiparallel currents repel.

9. Can Fleming's hand rules be used for alternating currents?

Yes, Fleming's hand rules can be used for alternating currents, but with consideration of the changing current direction. For AC, the force (in the Left Hand Rule) or induced current (in the Right Hand Rule) will alternate in direction as the current changes. This results in vibration in motors or alternating current in generators, respectively.

10. What common mistakes do students make when applying Fleming's hand rules?

Common mistakes include: confusing the Left and Right Hand Rules, incorrectly assigning fingers to the relevant quantities, not keeping fingers perpendicular, using the wrong hand for negatively charged particles, and forgetting to consider the actual geometry of the conductor and field in real-world problems.

11. How do Fleming's hand rules apply in the case of a charged particle moving in a magnetic field?

For a charged particle moving in a magnetic field, you can use a modified version of Fleming's Left Hand Rule. The first finger represents the magnetic field, the second finger represents the velocity of the particle (instead of current), and the thumb represents the force on the particle. For negatively charged particles, use your right hand instead.

12. Why is it important to keep the thumb, first finger, and second finger perpendicular in Fleming's rules?

Keeping the thumb, first finger, and second finger perpendicular in Fleming's rules is crucial because it represents the fundamental relationship between the three vectors involved: magnetic field, current (or motion), and force (or induced current). These quantities are always perpendicular to each other in electromagnetic interactions. The perpendicular arrangement of fingers helps visualize this relationship accurately.

13. Can Fleming's Left Hand Rule be used for negatively charged particles?

No, Fleming's Left Hand Rule is specifically designed for conventional current flow (positive charge movement). For negatively charged particles, like electrons, you should use the right hand instead, keeping the same finger assignments. This is because the force on a negative charge will be in the opposite direction to that on a positive charge in the same field.

14. What is the significance of the cross product in Fleming's hand rules?

The cross product is fundamental to Fleming's hand rules because it mathematically represents the perpendicular relationship between the vectors involved. In the Left Hand Rule, the force is the cross product of current and magnetic field (F = I × B). In the Right Hand Rule, the induced EMF is related to the cross product of velocity and magnetic field (ε = v × B). The hand rules provide a visual representation of these cross products.

15. How do Fleming's hand rules relate to the right-hand grip rule for magnetic fields around a wire?

While Fleming's hand rules and the right-hand grip rule are all used in electromagnetism, they serve different purposes. The right-hand grip rule determines the direction of the magnetic field around a current-carrying wire, whereas Fleming's rules determine force on a conductor (Left Hand) or induced current (Right Hand) when a conductor and magnetic field interact. These rules complement each other in understanding electromagnetic phenomena.

16. Can Fleming's Right Hand Rule be used to determine the direction of magnetic field in a solenoid?

No, Fleming's Right Hand Rule is not used to determine the magnetic field direction in a solenoid. For a solenoid, you should use the right-hand grip rule: wrap your right hand around the solenoid with your fingers in the direction of current flow, and your thumb will point in the direction of the magnetic field inside the solenoid.

17. What is Fleming's Left Hand Rule and how is it used?

Fleming's Left Hand Rule is a method used to determine the direction of motion of a current-carrying conductor in a magnetic field. Hold your left hand with the thumb, first finger, and second finger at right angles to each other. The first finger represents the magnetic field direction, the second finger represents the current direction, and the thumb shows the direction of the force or motion of the conductor.

18. How does the magnitude of the magnetic field affect the force in Fleming's Left Hand Rule?

The magnitude of the magnetic field directly affects the force on the current-carrying conductor. According to the equation F = BIL (where F is force, B is magnetic field strength, I is current, and L is length of conductor), increasing the magnetic field strength will proportionally increase the force on the conductor, assuming current and length remain constant.

19. How does changing the angle between the conductor and magnetic field affect the force in Fleming's Left Hand Rule?

The angle between the conductor and magnetic field significantly affects the force. The force is maximum when the conductor is perpendicular to the magnetic field and zero when it's parallel. This relationship is described by the equation F = BIL sinθ, where θ is the angle between the conductor and the magnetic field. As θ approaches 90°, sinθ approaches 1, maximizing the force.

20. How do Fleming's hand rules apply in three-dimensional space?

Fleming's hand rules apply in three-dimensional space by considering the vectors (magnetic field, current/motion, and force/induced current) in any orientation. The rules still hold: the resulting vector (force or induced current) will always be perpendicular to the plane formed by the other two vectors. This allows for analysis of electromagnetic interactions in complex 3D configurations.

21. Why don't we use a single hand rule for both motor and generator effects?

We don't use a single hand rule for both effects because the relationships between the vectors are different in each case. In the motor effect (Left Hand Rule), we start with current and magnetic field to find force. In the generator effect (Right Hand Rule), we start with motion and magnetic field to find induced current. Using separate rules helps avoid confusion and clearly distinguishes between these two related but distinct phenomena.

22. What happens if you accidentally use the Right Hand Rule for a motor effect problem?

If you accidentally use the Right Hand Rule for a motor effect problem, you will get the wrong direction for the force or motion of the conductor. This is because the Right Hand Rule is designed for generator effects, not motor effects. Always ensure you're using the correct rule for the given problem to avoid errors.

23. How does Fleming's Right Hand Rule differ from the Left Hand Rule?

Fleming's Right Hand Rule is used to determine the direction of induced current in a conductor moving in a magnetic field. The thumb represents the motion of the conductor, the first finger represents the magnetic field direction, and the second finger shows the direction of the induced current. The key difference is that the Left Hand Rule is for motors (force on a current-carrying conductor), while the Right Hand Rule is for generators (induced current in a moving conductor).

24. Can Fleming's Left Hand Rule be used to determine the direction of induced current?

No, Fleming's Left Hand Rule cannot be used to determine the direction of induced current. It is specifically used to find the direction of force on a current-carrying conductor in a magnetic field. For induced current, you should use Fleming's Right Hand Rule.

25. Why do we need two different hand rules for electromagnetism?

We need two different hand rules because they apply to different electromagnetic phenomena. The Left Hand Rule is used for the motor effect (force on a current-carrying conductor in a magnetic field), while the Right Hand Rule is used for the generator effect (induced current in a conductor moving through a magnetic field). These rules help visualize the relationships between motion, current, and magnetic fields in different scenarios.

26. Can Fleming's hand rules be applied to curved conductors?

Yes, Fleming's hand rules can be applied to curved conductors, but with some modifications. For a curved conductor, you need to consider the direction of the magnetic field and current (or motion) at each point along the curve. The resulting force or induced current will be perpendicular to both the field and current (or motion) at each point, potentially causing a complex motion or current distribution.

27. How do Fleming's hand rules apply to electromagnetic waves?

While Fleming's hand rules are primarily used for conductors in magnetic fields, they can help understand electromagnetic waves. In an EM wave, the electric field, magnetic field, and direction of propagation are mutually perpendicular, similar to the finger arrangements in Fleming's rules. This perpendicular relationship is crucial for the propagation of EM waves.

28. How does the concept of magnetic dipole moment relate to Fleming's hand rules?

While Fleming's hand rules don't directly deal with magnetic dipole moments, they are related. The magnetic dipole moment of a current loop is perpendicular to the plane of the loop. When such a loop is placed in an external magnetic field, it experiences a torque. This torque can be understood using Fleming's Left Hand Rule applied to different segments of the loop.

29. How do Fleming's hand rules relate to Lenz's law?

Fleming's Right Hand Rule is consistent with Lenz's law, which states that the direction of an induced current is such that it opposes the change that caused it. When using the Right Hand Rule, the induced current direction (given by the second finger) will always be in a direction that creates a magnetic field opposing the motion or change in the original magnetic field.

30. How does Fleming's Left Hand Rule apply to a loop of wire in a magnetic field?

For a loop of wire in a magnetic field, Fleming's Left Hand Rule applies to each segment of the loop individually. The force on each segment is perpendicular to both the current in that segment and the magnetic field. The net effect on the loop depends on the orientation of the loop relative to the field. If the loop is not aligned with the field, it will experience a torque, causing it to rotate.

31. How do Fleming's hand rules relate to the concept of magnetic flux?

Fleming's hand rules, particularly the Right Hand Rule, are closely related to magnetic flux. The Right Hand Rule helps determine the direction of induced current when there's a change in magnetic flux through a conductor. The magnitude of the induced EMF is proportional to the rate of change of magnetic flux, as described by Faraday's law of induction.

32. How do Fleming's hand rules relate to the concept of electromagnetic induction?

Fleming's Right Hand Rule is directly related to electromagnetic induction. It helps determine the direction of induced current in a conductor moving through a magnetic field or experiencing a changing magnetic field. This rule is a practical application of Faraday's law of induction, which describes how changing magnetic fields induce electric currents.

33. Why is it important to consider the right-hand coordinate system when using Fleming's rules?

The right-hand coordinate system is important because Fleming's rules are based on this convention. It ensures consistency in determining vector directions. In this system, if you point your thumb in the x-direction and your first finger in the y-direction, your second finger will naturally point in the z-direction. This aligns with the perpendicular relationships in electromagnetic phenomena.

34. How do Fleming's hand rules apply to a rotating coil in a magnetic field?

For a rotating coil in a magnetic field (like in an AC generator), Fleming's Right Hand Rule applies at each point in the rotation. As the coil rotates, the direction of motion of each segment changes relative to the magnetic field. By applying the Right Hand Rule throughout the rotation, you can determine how the induced current changes, explaining the sinusoidal nature of AC generation.

35. Can Fleming's hand rules be used to understand the working of a cyclotron?

Yes, Fleming's Left Hand Rule (modified for charged particles) can help understand the cyclotron. In a cyclotron, charged particles move in a spiral path due to a magnetic field. The Left Hand Rule explains why the particles curve: the magnetic force is always perpendicular to both the particle's velocity and the magnetic field, causing circular motion. The acceleration is provided by electric fields in gaps between the dees.

36. How do Fleming's hand rules relate to the concept of Lorentz force?

Fleming's Left Hand Rule is essentially a visual representation of the Lorentz force law for a current-carrying conductor. The Lorentz force law states that F = q(E + v × B), where q is charge, E is electric field, v is velocity, and B is magnetic field. For a current in a magnetic field (ignoring electric field), this reduces to F = IL × B, which is what the Left Hand Rule represents visually.

37. Can Fleming's hand rules be applied to superconductors?

Yes, Fleming's hand rules can be applied to superconductors, but with some considerations. In superconductors, the behavior of magnetic fields is unique (Meissner effect). However, for current-carrying superconductors in external magnetic fields, the Left Hand Rule can still be used to determine the direction of the force experienced by the superconductor.

38. How do Fleming's hand rules help in understanding the principle of electromagnetic braking?

Fleming's Right Hand Rule helps understand electromagnetic braking. When a conductor (like a metal disc) moves through a magnetic field, eddy currents are induced in the conductor. These currents create their own magnetic field, which opposes the motion (Lenz's law). The Right Hand Rule can be used to determine the direction of these induced currents and the resulting opposing force.

39. Can Fleming's hand rules be used to explain the behavior of charged particles in Earth's magnetic field?

Yes, a modified version of Fleming's Left Hand Rule can explain the behavior of charged particles in Earth's magnetic field. For instance, it can help understand the motion of cosmic rays or the formation of Van Allen radiation belts. The rule shows why charged particles often spiral along magnetic field lines and why they can become trapped in certain regions around Earth.

40. How do Fleming's hand rules apply in the case of a wire loop falling through a magnetic field?

For a wire loop falling through a magnetic field, Fleming's Right Hand Rule applies. As the loop falls, it cuts through magnetic field lines, inducing a current. The Right Hand Rule determines the direction of this induced current. The induced current then creates a magnetic field that opposes the motion (Lenz's law), explaining why the loop experiences a "magnetic drag" as it falls.

41. Can Fleming's hand rules be used to understand the principle of magnetic levitation?

Yes, Fleming's Left Hand Rule can help understand magnetic levitation. In maglev systems, strong electromagnets induce currents in conducting plates. These induced currents create their own magnetic fields. The Left Hand Rule can be used to determine the direction of the resulting force, which opposes gravity and leads to levitation. The interplay between induced currents and magnetic fields is key to magnetic levitation technology.

42. How do Fleming's hand rules relate to the concept of motional EMF?

Fleming's Right Hand Rule is directly related to motional EMF. Motional EMF is the electromotive force induced in a conductor moving through a magnetic field. The Right Hand Rule helps determine the direction of this induced EMF. The magnitude of the motional EMF is given by ε = Bvl, where B is the magnetic field strength, v is the velocity of the conductor, and l is its length.

43. Can Fleming's hand rules be applied to understand the working of a mass spectrometer?

Yes, Fleming's Left Hand Rule (modified for charged particles) can be applied to understand the mass spectrometer. In a mass spectrometer, charged particles move through a magnetic field. The Left Hand Rule explains why these particles follow curved paths: the magnetic force is always perpendicular to both the particle's velocity and the magnetic field. The radius of curvature depends on the particle's mass-to-charge ratio, allowing for separation of different ions.

44. How do Fleming's hand rules help in understanding the principle of a DC motor?

Fleming's Left Hand Rule is crucial for understanding DC motors. It explains the force on the current-carrying armature in the magnetic field of the motor. By applying the rule to different parts of the rotating armature, you can see how the motor continuously rotates. The commutator in a DC motor ensures that the current direction in the armature changes at the right moments to maintain rotation.

45. Can Fleming's hand rules be used to explain the behavior of diamagnetic materials?

While Fleming's hand rules don't directly explain diamagnetism, they can help understand the induced currents that cause diamagnetic behavior. When a diamagnetic material is placed in a magnetic field, tiny current loops are induced within the material. Fleming's Right Hand Rule can be used to determine the direction of these induced currents, which create a magnetic field opposing the external field.

46. How do Fleming's hand rules apply to the concept of magnetic flux cutting?

Fleming's Right Hand Rule is directly applicable to magnetic flux cutting. When a conductor moves across magnetic field lines (cutting the magnetic flux), an EMF is induced. The Right Hand Rule determines the direction of this induced EMF or current. The rate of flux cutting is proportional to the induced EMF, as described by Faraday's law of electromagnetic induction.