A force acts on a current-carrying conductor when it is kept in a magnetic field; the direction of this force may be established using Fleming’s Left-Hand Rule. Similarly, placing a moving conductor in a magnetic field induces an electric current in that conductor.
To identify the direction of the induced current, apply the Flemings Right Hand Rule. It’s important to note that these criteria don’t determine magnitude; instead, they show only the direction of the three parameters (magnetic field, current, and force) when the other two parameters are known.
‘Fleming’s Left-Hand Rule primarily applies to electric motors, whereas Fleming’s Right-Hand Rule mostly relates to electric generators.
Fleming’s Left-Hand Rule
When a current-carrying conductor is put in an external magnetic field, it feels a force perpendicular to both the field and the direction of the current flow. Three orthogonal axes on the thumb, forefinger and middle finger can be seen while holding a left hand, as indicated in the image.
“Perpendicular to one another, Make a fist with your left hand’s forefinger, second finger, and thumb. “If the forefinger symbolises the field direction and the second finger the current direction, the thumb represents the force direction.”
Facts To Keep in Mind
- It is employed in electric motors.
- The rule aims to determine the direction of motion in an electric motor.
- The thumb symbolises the push directly on the conductor.
- The index finger represents the magnetic field’s direction.
- The middle finger represents the direction of the current.
Fleming’s Right-Hand Rule
According to Faraday’s law of electromagnetic induction, a current is induced in a magnetic field when a moving conductor is put inside a magnetic field. There will be a link between the direction of applied force, magnetic field, and current if the conductor is pushed forcibly inside the magnetic field. Fleming’s right-hand rule determines this relationship between these three directions.
“Hold the fingers, middle finger, and thumb of your right hand at right angles to each other. Suppose the forefinger represents the direction of the magnetic field.
In that case, the thumb represents the direction of motion or applied force, and the middle finger represents the direction of the induced current. The middle finger indicates the direction of the induced current.”
Facts to Keep in Mind
- It is employed in the manufacture of electric generators.
- The rule aims to determine the direction of induced current as a conductor travels through a magnetic field.
- The thumb represents the conductor’s motion.
- The index finger represents the magnetic field’s direction.
- The middle finger shows the direction of the induced current.
General Observations
We can see that the left hand fulfils Motor, whereas the right hand satisfies Generator. The Fleming left-hand rule and Fleming right-hand rule are visual mnemonics (Mnemonics are learning strategies or memory aids that include an abbreviation, rhyme, or mental image that aids in remembering anything.).
In reality, these laws are never applied save as a handy technique to detect the direction of the consequence – either current or push. The Lorentz’ Force is the magnitude of force along this direction defined by these laws.
Lets Summarise
Let’s Take a conductor placed in a Magnetic Field.
If K is the length of the current-carrying conductor (rod), F is the force, and B is the magnetic field, then the equation is:
F = I * B * K
B = F / I * K
B = N/ A * m.
S.I. unit of I is A
S.I. unit of k is m.
and for B, it is Tesla.
Tesla = N / Am
Concept-Based Questions
Question 1 Assume the current flowing through the conductor is 3 A, the rod length is 6m, and the magnetic field is 3 T. Determine the amount of force created.
Answer
Given I = 3A, K = 6m, and B = 3 T
Since, F = I * B * K
= 3*6*3
F = 60N
Hence the force produced is 60 Newtons (N)
Question 2 In the wire, an electric current flows from right to left. Which way does the induced magnetic field point to the triangle’s location?
Answer Using Fleming’s left-hand rule, we can see that the force is pointing inwards and the magnetic field is heading downwards, into the screen, by rotating your middle finger in the direction of an electric current pointing in the appropriate direction.
Question 3 In a magnetic field, a current-carrying conductor does not rotate. What causes this to happen?
Answer: It signifies no force acting on the current-carrying conductor due to the magnetic field, implying that the current-carrying wire is parallel to the magnetic field.
Question 4 Is the magnetic field’s source equivalent to the source of electric current?
Answer No, since the magnetic field source is not a magnetic charge, whereas the electric field source is an electric charge.
Question 5 Determine the force exerted on the proton if it goes to by encountering a homogeneous magnetic field in the descending direction from the east.
Answer
We can identify the direction of the force exerted on the proton using Fleming’s left-hand rule.
Given that the proton is travelling eastward, the motion of the current is also eastward. Because the magnetic field is acting downwards, the force is directed north. As a result, we may say that the force is operating to the north.
Question 6 Determine the magnetic field direction if an electron travels vertically upwards and deflects to the south by a uniform magnetic field.
Answer We may identify the direction of the magnetic field acting on the electron using Fleming’s left-hand rule.
We already know that electrons have a negative charge. When an electron moves upward, the current travels in the opposite direction, that is, downward. The force acting on the electron is believed to be directed southward. As a result, the magnetic field is pointing east.
