Did you know that in a magnetic field current-carrying conductor will encounter force? It is called electromagnetic force or emf. All contemporary electric motors and generators are built around this feature. So, we know there's a force acting on the current-carrying conductor, but how do we know which way it's pulling? If only a simple procedure could be used in practically every circumstance. Well, Fleming's left-hand rule will do that.
Similarly, when a conductor is energized in a magnetic field, an induced current will be present in the conductor. By using Fleming's right-hand rule, power direction can be easily obtained.
Therefore, there is a connection between the magnetic field, and the force, and still in both laws. These rules do not indicate the size but indicate the direction of any of these parameters where the direction of the other two boundaries is known.
In the case of electric motors, Fleming's Left-handed rule applies, while Fleming's Right-handed rule applies to electric generators.
Understand Fleming’s Left Hand Rule
A force is exerted on the current-carrying conductor in a direction perpendicular to the direction of the magnetic field and current whenever it is set inside the magnetic field. It is mainly suitable to find the direction of the force.
It is stated as follows:
"Your left hand's forefinger, middle finger, and thumb should all be at a right angle (90degree) to one another the forefinger, middle finger, and thumb will all point in the same direction"
- Forefinger points in the direction of the magnetic field
- Middle finger points in the current direction
- Thumb points in the direction of force
Understand Fleming’s Right-Hand Rule
Faraday's law for the introduction of electromagnetic induction states that whenever a conductor is placed inside a magnetic field, the current induction will operate on it. There will be a relationship between the direction of the applied force, the magnetic field, and the current if the conductor is pushed firmly into the magnetic field. Fleming's right-hand rule determines the relationship between these three approaches.
It's stated as:
"Right finger, middle finger, and thumb should be right at each other. The middle finger will point toward the emf (or current) if the front finger points to the magnetic field and the thumb points the direction of conductor movement."
Know the Difference Between Fleming’s Left Hand and Right-Hand Rule
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Fleming’s Left Hand Rule |
Fleming’s Right Hand Rule |
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It applies to electric motors |
It applies to electric generators |
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Drive to find the magenta force direction in an electric motor. |
Find the induced force exerting in the electric generator. |
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Current direction is indicated by the middle finger |
Induced current direction is indicated by the middle finger |
We have learned the basics of Fleming's left hand and right hand rules. Let's now discuss a few questions related to this topic.
Tips to remember Fleming’s Left Hand & Right Hand Rule
Here are some tips to remember Fleming's left- and right-hand rules:
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Use a mnemonic
The initialism "FBI" can help you remember Fleming's right-hand rule. The letters stand for:- F: Force or motion
- B: Magnetic field
- I: Current
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Relate the fingers to the direction of the force, field, and current
According to Fleming's left-hand rule, the thumb denotes the direction of the force, the index finger shows the direction of the magnetic field, and the middle finger represents the direction of the current.
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Use the letter "g"
Since "right" and "generator" both have the letter "g," you may remember that Fleming's right-hand rule applies to generators.
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Remember that the rules only show direction
Fleming's left-hand and right-hand rules indicate the force, magnetic field, or current's direction but not its magnitude. The direction of the force acting on a conductor in a magnetic field can be ascertained using Fleming's left-hand rule, and the direction of the induced current in a conductor in a magnetic field can be ascertained using Fleming's right-hand method.
Concept-Based Questions
Question 1: If the electron is moving up and down in the south direction by the same magnetic field, find the direction of the magnetic field.
Solution: Fleming's left-hand rule is used to determine the direction of the electron magnetic field.
The electron has a negative charge, and when it goes upwards, the current direction goes downwards. As per the question, the electron magnetic field faces south. Thus, the east is the direction of the magnetic field.
Question 2: Suppose 5A is the current flowing in the conductor, 4m is the length of the rod, and the magnetic field is generated by 3 T. Find the force produced.
Solution:
As per the question given,
I = 5A, L = 4m and B = 3 T
F = I x L x B
= 5 x 4 x 3
F = 60 N
60 N is the force produced.
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Frequently Asked Questions
Q1. State Fleming’s right-hand rule
Ans. The direction in which the stream flows is determined by Fleming's right-hand rule. Directions of motion, field, and current induced in the conductor are represented by the thumb, forefinger, and center finger, respectively. According to the diagram, the thumb, index finger, and middle finger of the right hand are held at right angles to one another. When the conductor is moving in relation to the magnetic field, the thumb is pointing in that direction.
Q2. State Fleming’s left-hand rule
Ans. A current-carrying conductor in a magnetic field experiences a force perpendicular to the field and the direction of the current flow, according to Fleming's left-hand rule.
Q3. Which rule is used in electric motors?
Ans. The left-hand rule is applied in an electric motor because the electric current and magnetic field—the causes—lead to the force that generates motion as the result.
Q4. What is the purpose of Fleming’s right-hand rule?
Ans. Fleming's right-hand rule aims to identify the direction of induced current in a conductor as it moves through a magnetic field.
Q5. Which rule is used for electric generators?
Ans. Fleming's right-hand rule applies to electric generators. This rule shows the direction of the induced current when a conductor attached to a circuit moves in a magnetic field. It is helpful in determining the direction of a generator's current flows via its windings.
