Slide 1

• Topic: Diamagnetic, Paramagnetic, and Ferromagnetic Materials
• Introduction:
  • Materials can be classified based on their magnetic properties.
  • Diamagnetic materials, paramagnetic materials, and ferromagnetic materials are the three main types.
• Diamagnetic Materials:
  • Definition: Materials that are weakly repelled by a magnetic field.
  • Examples: Bismuth, Copper, Water, etc.
• Paramagnetic Materials:
  • Definition: Materials that are weakly attracted to a magnetic field.
  • Examples: Aluminum, Platinum, Oxygen, etc.

Slide 2

• Ferromagnetic Materials:
  • Definition: Materials that exhibit a strong magnetic response to a magnetic field.
  • Examples: Iron, Nickel, Cobalt, etc.
• Differences between Diamagnetic, Paramagnetic, and Ferromagnetic Materials:
  1. Diamagnetic materials have no unpaired electrons, while paramagnetic and ferromagnetic materials do.
  2. Paramagnetic materials have unpaired electrons, but they are randomly oriented.
  3. In ferromagnetic materials, unpaired electrons are aligned parallel to each other.
• Magnetic susceptibility:
  • Diamagnetic materials have negative magnetic susceptibility.
  • Paramagnetic materials have positive magnetic susceptibility.
  • Ferromagnetic materials have a very high magnetic susceptibility.

Slide 3

• Magnetic Field of the Earth
• Earth’s Magnetic Field:
  • Earth behaves like a giant magnet due to the presence of its solid inner core made of iron and nickel.
  • The magnetic field of the Earth is responsible for the direction and strength of a compass needle.
• Components of Earth’s Magnetism:
  1. Geographic North Pole: The point where the Earth’s axis of rotation intersects the Earth’s surface.
  2. Magnetic North Pole: The point towards which a compass needle points.
  3. Magnetic Declination: The angle between the geographic and magnetic north poles on a specific location.

Slide 4

• Magnetic Field Lines:
  • Magnetic field lines depict the direction and strength of a magnetic field.
  • They are represented using field lines that form closed loops.
  • The direction of the field lines is from the North pole to the South pole of a magnet.
• Characteristics of Magnetic Field Lines:
  1. They do not intersect.
  2. They are closer together where the magnetic field is stronger.
  3. They are farther apart where the magnetic field is weaker.

Slide 5

• Magnetic Field around a Bar Magnet:
  • A bar magnet exhibits a magnetic field around it.
  • The magnetic field has both magnitude and direction.
• Magnetic Field Lines around a Bar Magnet:
  • The magnetic field lines form continuous loops around the bar magnet.
  • Inside the magnet, the field lines extend from the South pole to the North pole.
  • Outside the magnet, the field lines extend from the North pole to the South pole.

Slide 6

• Magnetic Field Due to an Electric Current:
  • An electric current produces a magnetic field around it.
  • The direction of the magnetic field can be determined using the right-hand rule.
• Right-Hand Rule for a Current-Carrying Conductor:
  1. Point the thumb of your right hand in the direction of the current.
  2. Wrap your fingers around the conductor.
  3. The direction in which your fingers curl indicates the direction of the magnetic field.
• Magnetic Field Lines around a Current-Carrying Conductor:
  • The magnetic field lines form concentric circles around the conductor.

Slide 7

• Ampere’s Circuital Law:
  • Ampere’s Circuital Law relates the magnetic field around a closed loop to the total current passing through the loop.
  • Mathematically, it can be expressed as: ∮ B · dl = μ₀I where:
    • ∮ B · dl represents the line integral of the magnetic field.
    • μ₀ is the permeability of free space.
    • I is the total current passing through the loop.
• Applications of Ampere’s Circuital Law:
  • Calculating the magnetic field around a long solenoid.
  • Determining the magnetic field inside a current-carrying wire.

Slide 8

• Magnetic Field Due to a Circular Loop:
  • A circular loop carrying a current generates its own magnetic field.
  • The direction of the magnetic field can be determined using the right-hand rule.
• Right-Hand Rule for a Current-Carrying Circular Loop:
  1. Hold the loop with your right hand such that your thumb points in the direction of the current.
  2. The curling fingers indicate the direction of the magnetic field inside the loop.
• Magnetic Field Lines of a Current-Carrying Circular Loop:
  • The magnetic field lines are concentric circles that lie in the plane of the loop.

Slide 9

• Magnetic Field Near a Straight Current-Carrying Conductor:
  • A straight current-carrying conductor produces a magnetic field around it.
  • The direction of the magnetic field can be determined using the right-hand rule.
• Right-Hand Rule for a Straight Current-Carrying Conductor:
  1. Point your thumb in the direction of the current flowing through the conductor.
  2. The direction in which your curled fingers point indicates the direction of the magnetic field.
• Magnetic Field Lines near a Straight Current-Carrying Conductor:
  • The magnetic field lines form concentric circles around the conductor.

Slide 10

• Magnetic Field Due to a Solenoid:
  • A solenoid is a long coil of wire with multiple turns.
  • When a current passes through a solenoid, it produces a magnetic field.
• Magnetic Field Lines of a Solenoid:
  • The magnetic field lines inside a solenoid are parallel and close together, resembling a bar magnet.
  • The magnetic field lines outside the solenoid are weak and resemble those around a straight current-carrying conductor. "

Slide 11

• Magnetic Field Inside a Solenoid:
  • The magnetic field inside a solenoid is uniform and strong.
  • The direction of the magnetic field lines is from the South pole to the North pole.
• Factors Affecting the Magnetic Field Inside a Solenoid:
  1. Number of turns in the solenoid: Increasing the number of turns increases the magnetic field strength.
  2. Current flowing through the solenoid: Increasing the current increases the magnetic field strength.
  3. Length of the solenoid: Increasing the length decreases the magnetic field strength.

Slide 12

• Magnetic Force on a Current-Carrying Conductor:
  • A current-carrying conductor placed in a magnetic field experiences a force.
• Magnetic Force on a Straight Current-Carrying Conductor:
  • The magnitude of the magnetic force can be calculated using the formula: F = BILsinθ where:
    • F is the magnetic force,
    • B is the magnetic field strength,
    • I is the current in the conductor,
    • L is the length of the conductor,
    • θ is the angle between the magnetic field direction and the current direction.

Slide 13

• Magnetic Force on a Current-Carrying Loop:
  • A current-carrying loop placed in a magnetic field experiences a torque.
  • The torque causes the loop to rotate.
• Magnetic Torque on a Current-Carrying Loop:
  • The magnitude of the torque can be calculated using the formula: τ = BIA*sinθ where:
  • τ is the torque,
  • B is the magnetic field strength,
  • I is the current in the loop,
  • A is the area of the loop,
  • θ is the angle between the magnetic field direction and the normal to the loop.

Slide 14

• Magnetic Force on Moving Charges:
  • When a charged particle moves through a magnetic field, it experiences a perpendicular magnetic force.
• Magnetic Force on a Moving Charge:
  • The magnitude of the magnetic force can be calculated using the formula: F = qvBsinθ where:
  • F is the magnetic force,
  • q is the charge of the particle,
  • v is the velocity of the particle,
  • B is the magnetic field strength,
  • θ is the angle between the velocity vector and the magnetic field direction.

Slide 15

• Magnetic Force on a Current-Carrying Wire in a Magnetic Field:
  • When a current-carrying wire is placed in a magnetic field, it experiences a force.
• Magnetic Force on a Current-Carrying Wire:
  • The magnitude of the magnetic force can be calculated using the formula: F = BILsinθ where:
  • F is the magnetic force,
  • B is the magnetic field strength,
  • I is the current in the wire,
  • L is the length of the wire segment in the magnetic field,
  • θ is the angle between the magnetic field direction and the direction of the wire.

Slide 16

• Magnetic Flux:
  • Magnetic flux is a measure of the magnetic field passing through a given area.
  • Mathematically, it is represented as: Φ = B⊥A where:
  • Φ is the magnetic flux,
  • B⊥ is the component of the magnetic field perpendicular to the area A.
• Units of Magnetic Flux:
  • The SI unit of magnetic flux is Weber (Wb) or Tm² (Tesla meter squared).
  • 1 Weber = 1 Tm².

Slide 17

• Faraday’s Law of Electromagnetic Induction:
  • When the magnetic field passing through a loop changes, an electromotive force (emf) is induced in the loop.
• Faraday’s Law:
  1. The emf induced in a loop is directly proportional to the rate of change of magnetic flux through the loop.
  2. The induced emf is given by the equation: ε = -N(dΦ/dt) where:
  • ε is the induced emf,
  • N is the number of turns in the loop,
  • dΦ/dt is the rate of change of magnetic flux.

Slide 18

• Lenz’s Law:
  • Lenz’s Law states that the direction of the induced current (or emf) is such that it opposes the change in the magnetic field causing it.
• Applying Lenz’s Law:
  1. If the magnetic flux through a loop is increasing, the induced current flows in a direction to create a magnetic field opposing the increase in flux.
  2. If the magnetic flux through a loop is decreasing, the induced current flows in a direction to create a magnetic field opposing the decrease in flux.
• This law is a consequence of the law of conservation of energy.

Slide 19

• Applications of Electromagnetic Induction:
  1. Electric Generators: Convert mechanical energy into electrical energy by electromagnetic induction.
  2. Transformers: Change the voltage of an alternating current using electromagnetic induction.
  3. Induction Cooktops: Generate heat by inducing eddy currents in the cooking vessel.
  4. Magnetic Resonance Imaging (MRI): A medical imaging technique that uses electromagnetic induction to produce detailed images of the internal body structure.
  5. Inductive Charging: Used in wireless charging systems for smartphones and electric vehicles.

Slide 20

• Electromagnetic Waves:
  • Electromagnetic waves are transverse waves consisting of mutually perpendicular electric and magnetic fields.
  • They do not require a medium for propagation and can travel through a vacuum.
• Properties of Electromagnetic Waves:
  1. Speed: Electromagnetic waves travel at the speed of light in a vacuum, which is approximately 3 × 10^8 m/s.
  2. Frequency and Wavelength: Electromagnetic waves have a wide range of frequencies and wavelengths, forming the electromagnetic spectrum.
  3. Energy and Intensity: The energy and intensity of electromagnetic waves depend on their frequency. <slide 21>
• Electromagnetic Spectrum:
  • The electromagnetic spectrum is the range of all possible frequencies of electromagnetic radiation.
  • It includes radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays.
  • Each region of the spectrum has unique properties and applications. <slide 22>
• Radio Waves:
  • Radio waves have the longest wavelengths and lowest frequencies in the electromagnetic spectrum.
  • They are used for communication, broadcasting, and radar systems.
  • Example: Television and radio transmissions.
• Microwaves:
  • Microwaves have shorter wavelengths and higher frequencies than radio waves.
  • They are used for cooking, telecommunications, and radar systems.
  • Example: Microwave ovens, satellite communications. <slide 23>
• Infrared Radiation:
  • Infrared radiation has longer wavelengths and lower frequencies than visible light.
  • It is used for heating, night vision, and remote controls.
  • Example: Heat lamps, thermal imaging cameras.
• Visible Light:
  • Visible light is the portion of the electromagnetic spectrum that is visible to the human eye.
  • It consists of different colors with different wavelengths.
  • Example: Sunlight, LED lights. <slide 24>
• Ultraviolet Radiation:
  • Ultraviolet radiation has shorter wavelengths and higher frequencies than visible light.
  • It is used in sterilization, fluorescence, and tanning.
  • Example: UV lamps, sunlight.
• X-rays:
  • X-rays have shorter wavelengths and higher frequencies than ultraviolet radiation.
  • They are used in medical imaging, airport security, and scientific research.
  • Example: X-ray machines, CT scans. <slide 25>
• Gamma Rays:
  • Gamma rays have the shortest wavelengths and highest frequencies in the electromagnetic spectrum.
  • They are used in cancer treatment, sterilization, and nuclear medicine.
  • Example: Gamma-ray detectors, radiation therapy.
• Applications of Electromagnetic Waves:
  • Communication: Radio waves, microwaves, and satellite communication.
  • Medicine: X-rays, gamma rays, and MRI imaging.
  • Remote Sensing: Infrared, microwave, and satellite imaging.
  • Astrophysics: Radio waves, visible light, and gamma rays. <slide 26>
• Reflection of Light:
  • When light hits a surface, it can bounce back, which is known as reflection.
  • The angle of incidence is equal to the angle of reflection.
  • Law of reflection: θi = θr
• Refraction of Light:
  • Refraction occurs when light passes from one medium to another, causing it to change direction.
  • The change in direction is due to the change in the speed of light in different media.
  • Snell’s Law relates the incident angle, refractive index, and angle of refraction. <slide 27>
• Concave Mirror:
  • A concave mirror curves inward and converges light.
  • Depending on the distance of the object, it can form real or virtual images.
  • Examples: Makeup mirrors, reflector telescopes.
• Convex Mirror:
  • A convex mirror curves outward and diverges light.
  • It always forms virtual images that are smaller than the object.
  • Examples: Side mirrors on vehicles, security mirrors. <slide 28>
• Concave Lens:
  • A concave lens is thinner at the center and causes light to diverge.
  • It forms only virtual and reduced images.
  • Examples: Glasses for nearsightedness, binoculars.
• Convex Lens:
  • A convex lens is thicker at the center and causes light to converge.
  • It can form real or virtual images depending on the position of the object.
  • Examples: Magnifying glasses, cameras. <slide 29>
• Optical Instruments:
  • Microscopes: Use lenses to magnify small objects and make them visible.
  • Telescopes: Gather and focus light from distant objects for observation.
  • Cameras: Capture and record images using lenses and light-sensitive sensors.
  • Projectors: Display images or videos onto screens using lenses and light sources. <slide 30>
• Optical Phenomena:
  • Dispersion: The separation of white light into its constituent colors by a prism.
  • Interference: The interaction of two or more light waves that results in the formation of dark or bright regions.
  • Diffraction: The bending and spreading of waves around obstacles or edges.
  • Polarization: The restriction of light vibrations to a single plane by filtering or reflection.