ELECTROMAGNETICS TOPIC 2 ( PRELIMINARY CONCEPTS)
- 1. ELECTROMAGNETICS PRELIMINARY CONCEPTS BY: ENGR. ROUISE MICHAEL P. NARAGA ECT
- 2. Key Concepts Electric & Magnetic Fields: Has fundamental forces responsible for electrical and magnetic interactions. Electromagnetic Waves: Oscillating electric and magnetic fields that propagate through space. High-Frequency Effects: “As frequency increases, wavelength decreases” Wavelength formula: Electromagnetic waves propagate at the speed of light (c ≈ 3.00 × 10⁸ m/s) in free space.
- 3. Electromagnetic Spectrum The RANGE of all possible frequencies of electromagnetic waves, spanning from DC (0 Hz) to at least 10² Hz ⁰ . At DC (0 Hz), electromagnetics is divided into: Electrostatics: Study of stationary electric fields. Magnetostatics: Study of stationary magnetic fields. At higher frequencies, electric and magnetic fields interact to form propagating waves.
- 4. Regime Frequency Range Wavelength Range Gamma-Ray > 3 × 10¹ Hz ⁹ < 0.01 nm X-Ray 3 × 10¹ – 3 × 10¹ Hz ⁶ ⁹ 10 – 0.01 nm Ultraviolet 2.5 × 10¹ – 3 × 10¹ Hz ⁵ ⁶ 120 – 10 nm Optical (Light) 4.3 × 10¹ – 2.5 × 10¹ Hz ⁴ ⁵ 700 – 120 nm Infrared (IR) 300 GHz – 4.3 × 10¹ Hz ⁴ 1 mm – 700 nm Radio 3 kHz – 300 GHz 100 km – 1 mm Electromagnetic Spectrum Regions
- 5. NOTABLE REGIONS: (Radio spectrum)
- 6. NOTABLE REGIONS: (visible light spectrum) Color Frequency Wavelength Violet 668–789 THz 450–380 nm Blue 606–668 THz 495–450 nm Green 526–606 THz 570–495 nm Yellow 508–526 THz 590–570 nm Orange 484–508 THz 620–590 nm Red 400–484 THz 750–620 nm
- 7. Fundamentals of Waves two primary types of waves: transverse waves: Particles in the medium move perpendicular to the direction of the wave propagation, creating crests and troughs. longitudinal waves: Particles in the medium move parallel to the direction of the wave propagation, creating compressions and rarefactions. Example: sound waves.
- 8. Fields and Electric Field Intensity Definition of a Field A field is a continuum of values of a quantity as a function of position and time. Fields can be: Scalar fields: ex. electric potential (F). Vector fields: ex. electric field intensity (E) (X, Y, Z)
- 10. Electric Potential Difference Voltage (electric potential difference) is defined as energy per unit charge: WORK = FORCE (same unit “Joules”) BUT, it depends on their fields
- 12. Electric Field Due To A Point Charge The electric field due to a point charge (E) at a distance (R) in free space or any uniform medium is given by:
- 13. Unit vector pointing radially outward from the charge The unit vector pointing radially outward from a point charge is given by:
- 14. Electric Flux The integral of the electric field over a surface gives the flux or
- 15. Electric Flux Density Is an alternative way to describe an electric field, particularly useful in materials with varying permittivity
- 16. PERMITTIVITY Permittivity of Free Space The permittivity of a vacuum is a fundamental constant: Air has a permittivity close to free space permitivitty and is often approximated as such in calculations.
- 17. Relative Permittivity It is often more useful to express permittivity relative to free space.
- 18. Dielectric constant Dielectric constant is another name for relative permittivity The term “dielectric constant” is misleading because permittivity is relevant even for non-dielectric materials.