2. MAGNETIC INDUCTION
-Magnetic induction, also known as electromagnetic induction, is the process by which a
changing magnetic
field in a region of space induces an electric current or voltage in a nearby conductor.
-This phenomenon was discovered by Michael Faraday in the 19th century.
-According to Faraday’s law of electromagnetic induction, the induced electromotive force
(EMF) in a circuit is directly proportional to the rate of change of magnetic flux through
the circuit.
-This principle is the basis for many important technologies such as generators,
transformers, and inductors.
3. -Electricity from magnetism, known as electromagnetic induction, is the process
of generating an electric current or voltage by changing magnetic fields.
-This principle is vital for various technologies like generators and transformers,
where it’s used to convert mechanical energy into electrical energy or transfer
electricity between circuits.
ELECTRICITY FROM MAGNETISM
4. Michael Faraday, a brilliant scientist who
discovered electromagnetic induction in 1831.
5. -Faraday’s law of induction states that a change in magnetic flux through a loop of wire induces
an electromotive force (EMF) or voltage in the wire.
-This induced EMF creates an electric current in the wire if the circuit is closed. In simpler terms,
it means that moving a magnet near a coil of wire or changing the magnetic field within the coil
will generate an electric current in the wire.
-This principle is fundamental to the operation of electric generators, transformers,
and many other electrical devices
FARADAY’S LAW OF INDUCTION
6.
7. Unveiling Magnetic Flux: The Flow of Magnetism
Magnetic flux (4) is a concept in electromagnetism that describes the total amount of
magnetic field passing through a specific area. It's a way to quantify the strength and influence of
a magnetic field within a particular region. Imagine a magnetic field like an invisible current of
magnetism flowing through space. Each magnetic field line represents the path of this magnetic
influence. Magnetic flux is analogous to the flow rate of water in a pipe. Here's a breakdown of
the key points:
Total Magnetic Field: Magnetic flux considers the strength of the magnetic field and the number
of field lines passing through an area. A stronger magnetic field with more concentrated lines will
have a higher magnetic flux compared to a weaker field with fewer lines passing through the
same area.
8. Area Perpendicular to Field Lines: The orientation of the area matters. Magnetic flux is
maximized when the area is perpendicular to the magnetic field lines. Imagine holding a
flat plate in front of a bar magnet. If the plate is held flat (perpendicular), many field lines
pass through it, resulting in high flux. If you tilt the plate, fewer lines pass
through, reducing the flux.
Here's an analogy to solidify the concept:
Think of water flowing through a pipe:
Magnetic Field Strength: Imagine the water pressure as the magnetic field strength. Higher
pressure signifies a stronger field.
Number of Field Lines: The number of water molecules flowing per second represents the
number of field lines passing through the area. More molecules equate to more lines.
Area: The pipe's cross-sectional area represents the area we're considering. A wider pipe allows
more water to flow (higher flux) compared to a narrow one for the same pressure.
9. By understanding magnetic flux, we can analyze how strongly
a magnetic field affects a particular region.
This concept plays a crucial role in various electromagnetic
phenomena, including Faraday's Law of Induction, which
we'll explore next.
10. The Flow of Magnetism: Unveiling Magnetic Field Lines
While magnetism doesn't physically flow like a liquid, we can use the concept of "flow" to visualize
how magnetic fields behave and interact with their surroundings.
Here's a breakdown to understand the flow of magnetism:
Magnetic Field Lines: A Visual Representation
Imagine a magnet, like a bar magnet. It has a north and south pole. We can't directly see the
magnetic field it creates, but we can visualize it using magnetic field lines. These lines are
imaginary lines that depict the direction and strength of the magnetic field at any point.
They originate from the north pole and terminate at the south pole, never intersecting.
The density of the lines indicates the strength of the magnetic field. More concentrated lines
represent a stronger field, while sparse lines depict a weaker field.
11. Visualizing the Flow
Imagine these magnetic field lines as invisible streams of magnetism flowing through space. The
lines show the direction a tiny magnetized compass needle would point if placed anywhere
on the line. Think of iron filings sprinkled around a magnet. The way the filings align themselves
along invisible lines depicts the flow of the magnetic field.
Properties of the Flow
Continuous Lines: Magnetic field lines are continuous. They don't abruptly stop or have breaks.
They either form closed loops (like around a bar magnet) or extend infinitely outward.
No Monopoles: Unlike electric fields, which have positive and negative charges(sources and sinks),
magnetic fields don't have isolated poles. They exist as closed loops or continuous lines.
12. Flow and Interaction
The flow of magnetism helps us understand how magnets interact Opposite poles
attract (lines converge), while like poles repel (lines diverge). The flow also explains how
moving magnets or changing currents can induce electric fields (Faraday's Law).
As the flow of magnetism changes, it creates an electric field in a conductor.
Limitations of the Analogy
It's important to remember that magnetic fields aren't actual fluids. They are a
manifestation of a force field. The flow analogy helps with visualization, but it doesn't
capture the full complexity of magnetic interactions.
13. Understanding the Flow: Key Takeaways
By understanding the flow of magnetism through magnetic field lines, we can:Visualize the
direction and strength of magnetic fields.Predict how magnets will interact with each other.
Explain the basis for electromagnetic induction (Faraday's Law). This concept is fundamental
in electromagnetism and helps us understand various phenomena,From the operation of
electric motors to the behavior of charged particles in a magnetic field.
Unveiling Magnetic Flux: The Essence of Magnetism Through an Area
Magnetic flux ($), denoted by the uppercase Phi symbol, is a crucial concept in
electromagnetism. It quantifies the total amount of magnetic field that passes through a
specific area. Imagine a river flowing through a bridge; magnetic flux is like the amount of
water flowing through the bridge opening at any given time. Here's a deeper dive into
magnetic flux:
14. Understanding the Essence
Magnetic Field & Area: Magnetic flux considers both the strength of the magnetic field and the
size and orientation of the area it interacts with,Stronger Field, Higher Flux: A stronger magnetic
field, with more concentrated field lines passing through a specific area, translates to a
higher magnetic flux.
Area Matters: The orientation of the area also plays a role. Magnetic flux is maximized when the
area is perpendicular to the magnetic field lines. Imagine holding a flat plate in front of a
bar magnet. If the plate is held flat, many field lines pass through it, resulting in high flux.
Tilting the plate reduces the number of lines passing through, lowering the flux.
Units and Measurement
The SI unit of magnetic flux is the weber (Wb). One weber represents one volt-second (Vs).
To calculate magnetic flux, we can use the following equation:BA cos(0)where: (Phi) is the
magnetic flux in webers (Wb) B is the magnetic field strength in teslas (T) A is the area of the
15. Key Points to Remember
Higher Magnetic Field Strength: A stronger magnetic field, with more concentrated lines,will result
a higher magnetic flux even for the same area. Larger Area: A larger area perpendicular to the field
lines will allow more lines to pass through, increasing the magnetic flux.
Angle Matters: The angle between the field and the area is crucial. If the area is not perpendicular
(090"), the effective area through which the field lines pass is reduced, lowering the flux
(cos(8) term in the equation).
Magnetic Flux and Everyday ApplicationsMagnetic flux plays a vital role in various areas:
Generators: Generators use rotating magnets to create a changing magnetic field that induces a
current in coils of wire. The amount of current generated is directly related to the magnetic
flux through the coils.
16. Transformers: Transformers use a changing magnetic flux to transfer electrical energy from
one circuit to another. By manipulating the number of turns in the coils, they can change the
voltage based on the principle of magnetic flux. Electric Motors: Electric motors utilize
electromagnets to create a rotating magnetic field.This changing magnetic field interacts with
permanent magnets in the motor, causing it to spin. The strength of the interaction depends on
the magnetic flux produced by the electromagnets.
Understanding magnetic flux is fundamental to grasping the interaction between magnetic fields
and conductors. It forms the foundation for numerous electromagnetic technologies that power
our world.
17. The Key to Induction: A Change in Magnetic Flux
Faraday's Law of Induction revolutionized our understanding of electromagnetism, This law
reveals a fascinating connection: a changing magnetic field can induce an electric cument in a
conductor. But what's the secret ingredient? The key les in a change in magnetic flux
Unveiling Magnetic Flux
Imagine a magnetic field like an invisible current of magnetism fowing through space. Each
magnetic field line represents the path of this magnetic influence. Magnetic flux () quantifies the
total amount of magnetic field passing through a specific area. Think of it like the flow rate of
water in a pipe.
Stronger Magnetic Field: A stronger magnetic field with more concentrated lines translates to a
higher magnetic flux Larger Area: A larger area perpendicular to the field lines allows more
lines to pass through. increasing the flux
18. The Spark of Change
Faraday's Law hinges on the concept of a changing magnetic flux through a conductor. The change
can occur in several ways:
Moving Magnet: Imagine a magnet being moved towards or away from a coll of wire. As the
magnet moves, the magnetic field lines passing through the coll's loops change. This change in
magnetic flux induces an electric current in the cof
Visualizing the Change
Imagine a coil of wire held near a magnet. As you move the magnet closer to the coll, more
magnetic field ines pass through the col's loops, signifying an increase in magnetic flux.
This change induces a current in the coil. Conversely moving the magnet away from the coil
reduces the flux, again inducing a current but in the opposite direction according to Lenz's Law
(covered in the next slide)
19. The Takeaway: Why Does Change Matter?
A constant magnetic field, even a strong one, won't induce a current in a conductor using
Faraday's Law, it's the change in the magnetic field that disrupts the existing magnetic environment
around the conductor. This disruption creates an electromotive force (emf). essentially a voltage
push that drives the flow of current in the conductor. The greater the change in magnetic flux, the
larger the induced emf and the stronger the current.
Examples of Change in Magnetic Flux:
Generators: Generators use rotating magnets to create a continuously changing magnetic field
through coils of wire. This changing flux induces a current in the ecoils, generating electricity
Changing Current: If a current flows through a coil of wire, it creates a magnetic field. By changing
the cument in the coil (Increasing or decreasing), the magnetic field also changes. This change in
magnetic field, in turn, can induce a current in another nearby coil
20. Understanding the importance of a changing magnetic flux is crucial for grasping Faraday's Law
and its numerous applications in our daily lives.
The Opposing Force: Unveiling Lenz’s Law
Faraday's Law of Induction tells us that a changing magnetic field can induce an electric current in
a conductor. But there's another crucial aspect to consider: Lenz's Law. This law explains the
direction of the induced current
Transformers: Transformers work by changing the magnetic flux through coils due to changes in
current. This allows them to transfer electrical energy at different voltage levels. Metal Detectors:
Metal detectors use a changing magnetic field to detect the presence of metal objects that alter
the magnetic field in their vicinity
21. Heinrich Friedrich Emil Lenz
Heinrich Lenz, a German physicist, formulated this law in 1834,
states that the induced current in a conductor always flows in a direction that creates a
magnetic field opposing the change in the original magnetic field. In simpler terms, the induced
current acts like a shield, trying to prevent the change in the magnetic field that produced it.
22. Visualizing the Opposition
Imagine a magnet being moved towards a coil of wine. As the magnet approaches, the magnetic
field lines passing through the coll increase. According to Lenz's Law, the induced current in the
coil will flow in a direction that generates its own magnetic field. This induced magnetic field will
oppose the increase in the original magnetic field caused by the approaching magnet
Herner's an analogy:
Imagine pushing a heavy door open. The door represents the original magnetic field. As you push
(causing a change), the door naturally resists your push (opposing the change) Similarly, the
induced current acts like an opposing force to the change in the original magnetic field.
Consequences of Lenz's Law Lenz's Law has several important consequences:
It helps us predict the direction of the induced current.
23. It explains why a changing magnetic field can transfer energy. The induced current does work to
oppose the change, which requires energy This energy comes from the source that's causing the
change in the magnetic field (eg, the movement of the magnet). It forms the basis for the
operation of many electromagnetic devices like generators and motors.
Examples of Lenz's Law in Action
Generators: In a generator, a rotating magnet induces a current in a coil. The induced current,
according to Lenz's Law, creates a magnetic field that opposes the rotation of the magnet. This
opposition requires energy, which comes from the mechanical force used to rotate the magnet.
Transformers: Transformers use changing magnetic fields to transfer electrical energy Lenz's Law
ensures that the induced current in the secondary coll creates a magnetic field that opposes the
change in the primary coil, allowing for efficient energy transfer.
24. Lenz's Law, coupled with Faraday's Law, provides a complete
picture of electromagnetic induction. It helps us understand
how changing magnetic fields create currents, predict in their
direction, and explains the energy transfer involved.
