Electromangnetic Radiation and the Electromagnetic Spectrum.pptx

A concise, summary of the wonderful phenomenon that is Electromagnetic Radiation and the Electromagnetic Spectrum.
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1. Electromagnetic Radiation Introduction of EM Radiation & Wave-Like Nature of EM Radiation 

2. Objectives of the Lesson: By the end of the lesson, the learners should be able to: State the two natures of Electromagnetic (EM) radiation; Briefly explain how EM waves propagate; Calculate the wavelength or the frequency, given one of the variables.

3. What is Electromagnetic Radiation? Electromagnetic (EM) radiation is a form of energy that travels through waves in what is called electromagnetic waves. These waves have electric and magnetic field components,  hence the name being "electro" + "magnetic".   The most common example of EM radiation is visible light.  This is due to the fact that we see things because of light reflecting off them and entering our eyes. However, there are more examples of electromagnetic radiation such as: UV (Ultraviolet) rays and X-rays.

4. Wave-Particle Duality of EM Radiation A special property of EM radiation is that they display properties of a wave and properties of a particle. At first, EM radiation seemed like a continuous wave but, when experiments were performed, it was seen that EM radiation also displayed properties of a particle. This is called the wave-particle duality of waves. However, one can not test the wave and particle nature at the same time. For this lesson, we will focus on the wave-like nature of EM radiation.

5. Wave-Like Nature of EM Radiation Watch the following video on the propagation of EM waves: https://youtube.com/shorts/imaJLR7JCwE?si=3OJhaKpFagPqc2Ms This video just gives a broad visualization on how EM waves propagate, but let's discuss what we saw in detail.  "Accelerating charges emit electromagnetic waves." When a charges accelerates, it produces a changing electric field. This changing electric field generates a changing magnetic field. The changing magnetic field in turn generates a changing electric field.  This is principle behind the propagation of EM waves. 

6. Wave-Like Nature of EM radiation: The following simulation best shows how the changing electric field and magnetic field interact: https://ophysics.com/em3.html In the simulation, the electric field oscillates in one plane and produces a magnetic field that oscillates in a plane perpendicular to the plane of the electric field. These EM waves travel a vacuum at a constant speed of 3 × 10 8 m/s This is the speed of light in a vacuum; Represented by c The EM waves travel slower when travelling through any given mediums than it would through a vacuum. 

7. Wave-Like Nature of EM Radiation Since EM radiation is a wave, the wave equation still applies: v = f × λ Where v is the speed of the wave; f is the frequency of the wave; λ is the wavelength Due to EM waves travelling at a constant speed, c, the equation above will change to be: c =  f × λ Where c is the speed of light in a vacuum Due to c being constant, the frequency and the wavelength of a wave have an inversely proportional relationship.  If f increases, then  λ decreases and visa versa

8. Worked Examples: Worked example 1:  Calculate the frequency of an electromagnetic wave with a wavelength of 4.2 × 10 -7 m. Use the formula, c = f ×  λ, to calculate the frequency (f).  c = f × λ 3 × 10 8 m/s = f × 4.2 × 10 -7 m f = 7.14 × 10 14 Hz

9. Worked Examples: Worked Example 2: Calculate the wavelength of a wave if the frequency is 1.5 × 10 15 Hz. Use the equation, c = f × λ, to calculate the wavelength of a wave. c = f × λ 3.0 × 10 8 m/s = 1.5 × 10 15 Hz × λ  Λ = 200 × 10 -9 m

10. Summary: EM radiation has wave-particle duality. Has properties of both a wave and a particle. EM radiation travels through space as EM waves. Waves both have electric and magnetic field components. EM waves propagate when an electric field oscillates in one plane and produces a magnetic field oscillating in a plane perpendicular to the plane with the plane of electric field.  EM waves travel at a constant speed through a vacuum (3 × 10 8 m/s). The equation, c = f ×  λ, can be used to calculate frequency (f) and wavelength (λ). Where c is constant ay 3 × 10 8 m/s

11. Consolidation Exercise: Complete the following Kahoot quiz: https://kahoot.it/challenge/04729337?challenge-id=8ff2affe-98ef-4517-9d7e-5137f73314c1_1745919458916