lesson 26.2 notes ppt and solving

Page 1: Overview of Electromagnetism

• Lesson Topic: Electromagnetism

• Focus: Electric and magnetic fields in space

Page 2: Electromagnetic Waves

• Definition: Electromagnetic waves (EMW) are coupled oscillating electric and magnetic fields.

• Contributors:

  • Oersted: Discovered that an electric current produces a magnetic field.

  • Faraday: Demonstrated that a changing electric current creates a changing magnetic field.

  • James Maxwell: Unified these concepts into four equations, predicting that electromagnetic waves could travel through space, confirmed by Hertz.

• Key Concept: Electric fields can exist and be induced without a physical wire.

Page 3: Properties of Electromagnetic Waves

• Production: Accelerating electrons create the electric and magnetic fields of a wave.

• Orientation: Both fields are perpendicular to the direction of wave propagation.

• Nature of Waves:

  • Transverse waves that travel in a vacuum at light speed (c = 3.00 x 10^8 m/s).

  • Speed remains constant in the same medium; as wavelength increases, frequency decreases.

• Example Problems:

  • Wavelength of green light (5.70 x 10^14 Hz).

  • Frequency calculations for various wavelengths.

Page 4: The Electromagnetic Spectrum

• Definition: The electromagnetic spectrum encompasses the range of frequencies of electromagnetic waves.

• Radiation Types:

  • Electromagnetic radiation carries energy proportional to the square of the electric field amplitude.

• Key Types and Frequencies:

  • Radio waves: </10^10 Hz to 10^16 Hz.

  • X-rays: Frequencies range from 10^16 Hz to 10^20 Hz.

Page 5: Uses of Low Frequency Waves

• Radio Waves: Longest wavelengths, used for broadcasting over long distances (broadcast radio, FM radio).

• Microwaves: Used in cellular phones, cooking, GPS.

• Infrared: Utilized in night vision, temperature measurement, optical fibers, remote control.

• Ultraviolet: Used in sterilization, curing polymers, and causing chemical reactions like sunburn.

Page 6: High Frequency Waves

• X-rays: Discovered through high energy electron collisions; useful for medical imaging and cancer treatment.

• Gamma Rays: High frequency from radioactive decay; used in cancer treatment and detection of hazardous materials in shipping.

Page 7: Propagation of Electromagnetic Waves Through Matter

• Dielectrics: Poor conductors of electric current whose electric charges partially align with electric field (e.g., air, glass, water).

• Velocity in Dielectrics: Slower than in a vacuum; defined by dielectric constant (K).

Page 8: Practice Problems on Wave Speed

• Problems calculating the speed of electromagnetic waves in air and water using the dielectric constant.

Page 9: Propagation Through Space

• Transmission: Radio and microwaves broadcast through antennas.

• Transmitter Functionality: Converts various signals (voice, music) to electromagnetic signals; creates oscillating electric fields.

Page 10: Producing Electromagnetic Waves

• Carrier Waves: Specific wavelengths used for communication; modulated for broadcasting.

• Components of a Transmitter: Typically include an oscillator, modulator, and amplifier to produce and enhance the signal.

Page 11: Modulation Techniques

• Amplitude Modulation (AM) vs. Frequency Modulation (FM): Changes in wave properties to encode data.

Page 12: Oscillation Mechanisms

• Oscillator Circuit: Generates potential difference creating electromagnetic waves through oscillation of electric fields.

Page 13: Sustaining Oscillations

• Continued Oscillation: Requires energy input to maintain oscillation due to energy losses in circuits.

• Transformers: Utilized to amplify signals in higher frequency circuits.

Page 14: Energy Conservation in Circuits

• Energy Analogy: Comparing energy transfer in circuits to a pendulum’s movement between potential and kinetic energy states.

Page 15: Advanced Wave Production Methods

• Resonant Cavity: A specialized apparatus for generating high-frequency microwaves related to physical dimensions.

• Piezoelectric Crystals: Generate electromagnetic fields through crystallization and deformation under electric fields.

Page 16: Receiving Electromagnetic Waves

• Antenna Function: Receives EMW by converting oscillating electric fields back into potential differences.

Page 17: Dish Antennas

• Design: Tailored to reflect and focus electromagnetic waves into the receiving apparatus.

Page 18: Information Transmission through EMW

• Modulation: Frequencies and amplitudes encode information; digital signals provide more bandwidth than analog signals.

Page 19: Wave Conversion to Information

• Receiver Functionality: Keywords include antenna, receiver, tuner adjustments to select desired frequencies and convert to usable output.

Page 20: Speed of Electromagnetic Waves in Different Media

• Speed equation: Variations in speed based on medium characterized using dielectric constants.

Page 21: Summary of Electromagnetic Wave Concepts

• Definition: Coupled electric and magnetic fields;

• Electromagnetic radiation: Energy directly relates to oscillation amplitude and medium frequency.

Page 22: Wave Properties and Relationships

• Wavelength and frequency correlation: Important for understanding EMW behavior and transmission in different media.

Page 23: Air vs. Other Materials

• Dielectric properties: Influence on electromagnetic wave propagation speed in various media.

Page 24: Modulation Types in Communication

• FM vs. AM Radio: Distinctions in reliability, noise sensitivity, and modulation methods.

Page 25: Applications of Microwave and Infrared Waves

• Microwaves: Applications in heating, cooking, and remote control devices.

• Infrared: Temperature measurement and communication functions.

Page 26: X-ray Production and Uses

• Mechanism: High potential differences generating X-ray production and their role in diagnostics and cancer treatment.

Page 27: Transmission Processes Explained

• Understanding Radio Waves: How they propagate and are transmitted effectively over distances.

Page 28: Broadcasting with Carrier Waves

• Carrier Wave Functionality: Essential for modulating and sending signals across devices.

Page 29: Components of EM Wave Transmission

• Core Parts of Transmitters: Detailed description of oscillator, modulator, and signal amplifier.

Page 30: Finding Wave Characteristics

• Using given formulas to compute wave properties based on observations and media calculations.

Page 31: Effective Transmission of EM Waves

• Antenna Alignment: Importance for effective wave detection and reception.

Page 32: Transmitter Component Functionality

• Parts of a Transmitter: In-depth functionality including the control over signal modulation and power amplification.

Page 33: Comprehensive EM Wave Transmission Explanation

• Mechanics of Transmitter Operation: Detailed steps in converting various data formats to EM waves using antennas.

Page 34: Understanding Coil-and-Capacitor Circuits

• Cycle and Field Mechanics: How oscillations in these circuits correlate with electromagnetic field strengths and charges.

Page 35: Mechanical vs. Electrical Energy in Circuits

• Energy Dynamics: Describing energy transitions between stored electric and magnetic forms.

Page 36: Frequency Consistency in Radio Waves

• Maintaining Constant Frequency: Techniques to ensure stable output power and wave propagation.

Page 37: Types of Oscillators in Frequency Production

• Variations in Design and Function: Discusses limitations and improvements in coil-capacitor and special resonance circuits.

Page 38: Receiving Wave Mechanisms Explained

• Functionalities of Antennas: Details the processes of signal reception, direction sensitivity, and receiver circuits.

Page 39: Comparison of Antenna Types

• Wire vs. Dish Antennas: Efficiency, design parameters, and applications in various frequencies.

Page 40: Practice Problems for EMW

• Example Calculations: Solving for wavelengths, frequencies, and comparing wave behavior through specified media.

Page 41: Advanced Practice Problems

• Problem-solving techniques applied to real-world conditions of electromagnetic transfers and signal dynamics.

Page 42: Wave Propagation Concepts

• Field Regeneration in Waves: Describing how electric and magnetic fields interact in wave dynamics.

Page 43: Electrons and Wave Reception

• Accelerating Electrons in Antennas: How radio waves influence electric field alignment and energy transfer.

Page 44: Implications of Wavelength on Biology

• Understanding Effects on Biology: Discusses perceptual implications of EM radiation at different wavelengths relative to biological systems.