Magnetism Right Hand Rule

A positive charge is moving upwards in a magnetic field directed towards the north. By Physics experts to help you in doubts & scoring excellent marks in Class 9 exams. If you find curling your fingers too confusing, you can try this method that uses your thumb, pointer finger, and middle finger all 90 degrees apart. The hardest part of right-hand rule is imagining the different axes and envisioning how they are perpendicular to each other.

Understand the basic concept of right-hand grip rule

The magnetism right hand rule plays a vital role in the design and operation of electromagnetic coils in speakers and headphones. The interaction between the current-carrying coil and the permanent magnet creates sound waves that produce the audio we hear. The hardest part of the right-hand rule is imagining the different axes and envisioning how they are perpendicular to each other. This is most likely because the same kind of orthogonality can be represented by various configurations of fingers, on either hand. Fingers can be outstretched orthogonally, or the palm can be flat (hence slap rule). If the electric charge has a negative value (e.g. electron) then the force acts in the opposite direction.

From predicting magnetic fields to understanding electromagnetic waves, this rule plays a crucial role in various applications, ranging from everyday devices like electric motors and speakers to cutting-edge technologies like MRI machines and particle accelerators. In particle accelerators, charged particles experience magnetic forces as they move through magnetic fields. Scientists use the magnetism right hand rule to design and control the trajectories of these particles, enabling cutting-edge research in physics. Magnetic compasses are essential navigation tools, and they operate based on the magnetism right hand rule. The compass needle aligns itself with Earth’s magnetic field, indicating the North-South direction. However, nowadays there are publications which refer to the Fleming’s left-hand rule for magnetic force in motors and right-hand rule for generators.27)28)29)

Make it easy to learn and understand

The “hand rules” for directions of magnetic force were proposed in 1890 by John Ambrose Fleming.10)11) All these rules are equivalent, because the direction of the physical magnetic force (Lorentz force) is always the same. From the diagram it is clear that the moment arm r is just the magnitude of the component ┴ vector, in the perpendicular-to-the-force direction, of the position vector of the point of application of the force.

Direction of magnetic force

As shown in the illustration, when looking from the end marked with “N”, the current appears to flow in the anticlockwise direction. At the same time, when looking from the end marked with “S”, the current appears to flow clockwise. Calculations of magnetic forces in three-dimensional space involve vector calculus, which by convention operates in a right-handed system, therefore right-hand rules (as outlined above) should be used accordingly. At a fundamental level it is not possible to calculate, in an absolute way, a value for binary quantities such as positive/negative (electric charge), clockwise/anticlockwise (direction of rotation), up/down (side of a surface), etc. They can only be defined with relation to each other, or to some closely related direction in the same system of coordinates.

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• For this, the wire needs to be held in the right hand and the thumb should point towards the direction of the flow of current then curl your fingers around the wire.
• The strength of each magnet reduces to half when it is cut along its length into the equal parts magnetic field strength of a solenoid.
• It should be kept in mind that this rule should only be performed with the right hand.
• If you find curling your fingers too confusing, you can try this method that uses your thumb, pointer finger, and middle finger all 90 degrees apart.
• It is used to show the rotation of a body or a magnetic field and represents the connection between the current and magnetic field around the wire.

Right hand rule can also be used for determination of the magnetic field orientation and direction MRI machines use powerful magnetic fields to visualize internal structures in the human body. Understanding the magnetism right hand rule is crucial for optimizing and directing these magnetic fields to obtain clear and accurate images.

• (If the axes do not have a positive or negative direction, then handedness has no meaning.)
• This phenomenon is the cornerstone of electric power generation and distribution.
• The right-hand grip rule is used to determine the relationship between the current and the magnetic field based upon the rotational direction.
• Ampère was inspired by fellow physicist Hans Christian Ørsted, who observed that needles swirled when in the proximity of an electric current-carrying wire and concluded that electricity could create magnetic fields.
• P1 and P2 are the positions of the magnetic compass, before and after passing a current through XY respectively.
• The various right- and left-hand rules arise from the fact that the three axes of three-dimensional space have two possible orientations.

However, in generators, the charges are originally moved because the wire is pushed by some input torque. The charges move together with the wire, and the magnetic force pushes them along the wire, thus creating an electromotive force (EMF). It should be noted here that the magnetic force for a positive charge always follows this rule, regardless of any other conditions. Therefore, exactly the same right-hand rule is applicable to both motors and generators. For such loop, the magnetic poles N and S appear at each end, and they can be distinguished by the stylised letters with arrows at their ends, which show the apparent direction of “rotation” of current in the loop.

Corkscrew Rule

In some literature this rule is discussed as if it was a separate rule from the one described in the section above, but it results from the same principles. The right hand is depicted with the thumb following the direction of the current in a straight wire, and curled fingers show the direction in which the magnetic field (flux density B or magnetic field strength H) circulating around the wire.19) In simple words, a current carrying conductor creates a magnetic field around it. The lines of magnetic flux are in the shape of concentric circles and perpendicular on the conductor (at right angle of 90o) as shown in fig. The direction of current and magnetic field can be found by the following rules i.e. right hand gripping rule, the end rule, corkscrew rule, Fleming’s left and right hand rules etc.

The right hand rule is used to determine the direction of the magnetic field lines and current around a straight current carrying conductor, solenoid or coil inductor. A Danish physicist Hans Christian Orsted in 1820 discovered the relation between electricity and magnetism which states that “when current flows in a straight conductor, a magnetic field is produced in it. The polarity and density of the magnetic field depends on the direction and amount of current flowing through the conductor”. One of the fascinating phenomena explained by the magnetism right hand rule is electromagnetic induction. This process occurs when a conductor moves through a magnetic field or when there is a change in the magnetic flux through a circuit. Electromagnetic induction is the foundation of various electrical devices, including generators and transformers.

Before we can analyze rigid bodies, we need to learn a little trick to help us with the cross product called the ‘right-hand rule’. We use the right-hand rule when we have two of the axes and need to find the direction of the third. When an electric charge oscillates or accelerates, it emits electromagnetic waves, which travel at the speed of light. Radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays are all examples of electromagnetic waves, each having different frequencies and wavelengths. Using these x and y, let’s use the right-hand rule to find the direction of z.

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Similarly, When the observer sees at the facing end of the coil, if current flows in the anticlockwise direction, then the facing end of the coil behaves like a North Pole “N” and the second end behaves like the South Pole “S”. When an observer looks at the facing end of the solenoid, if current flows in the clockwise direction, the the facing end of the solenoid coil behaves like the South Pole “S” and the second end behaves like the North Pole “N”.

The index finger shows the direction of the first vector, which in this case is the direction of the original movement of the positive charge $q$ which constitutes conventional electric current $I$. In an ordinary conductor if some voltage is applied across it the electrons will flow in the opposite direction, but it is the conventional current (flowing from plus to minus) which is taken into account here. This is done by using your right hand, aligning your thumb with the first vector and your index with the second vector.

In fact, in a real wire only the negatively charged electrons move, as the positively charged protons remain bound to the atoms, which are stationary with respect to the body of the wire. The thumb points in the third orthogonal direction, namely in the direction of the magnetic force $F$ acting on the charge moving in magnetic field. P1 and P2 are the positions of the magnetic compass, before and after passing a current through XY respectively.

There are two ways to do the right hand rule, and they take practice to conceptually understand, but this will make solving problems much quicker. Reversing the direction of one axis (or three axes) also reverses the handedness. Reversing two axes amounts to a 180° rotation around the remaining axis, also preserving the handedness.

By applying this rule, one can quickly right hand grip rule grasp the complex interactions between magnetic fields and electric currents. This logic is consistent with the application of the vector cross product, as explained above for the right-handed system of coordinates. To find whether the axis of rotation is positive or negative, curl your fingers in the direction of rotation and your thumb shows the direction of rotation, i.e. whether rotation is along the positive or negative x y or z direction.

When viewed at a position along the positive z-axis, the ¼ turn from the positive x- to the positive y-axis is counter-clockwise. The various right- and left-hand rules arise from the fact that the three axes of three-dimensional space have two possible orientations. This can be seen by holding your hands together with palms up and fingers curled. If the curl of the fingers represents a movement from the first or x-axis to the second or y-axis, then the third or z-axis can point along either right thumb or left thumb.

Unlike most mathematical concepts, the meaning of a right-handed coordinate system cannot be expressed in terms of any mathematical axioms. Rather, the definition depends on chiral phenomena in the physical world, for example the culturally transmitted meaning of right and left hands, a majority human population with dominant right hand, or certain phenomena involving the weak force. A list of physical quantities whose directions are related by the right-hand rule is given below. (Some of these are related only indirectly to cross products, and use the second form.) For left-handed coordinates, the above description of the axes is the same, except using the left hand; and the ¼ turn is clockwise.