Lesson 5: Electromagnetic Radiation
Overview:
Faraday's law describes how a changing magnetic field by itself can produce an electric field. Many physicists wondered if the reverse were possible, whether an electric field by itself could produce a magnetic field. Scottish physicist and mathematician James Clerk Maxwell hypothesized that this was possible. He proposed that a changing electric field produces a magnetic field. Maxwell expressed his theory of electromagnetism in four equations, generally called Maxwell's equations.
Curriculum Expectations:
Overall Expectations:
E1. Analyse technologies that use the wave nature of light, and assess their impact on society and the environment.
Specific Expectations:
E2.1 Use appropriate terminology related to the wave nature of light, including, but not limited to: diffraction, dispersion, wave interference, nodal line, phase, oscillate, polarization, and electromagnetic radiation.
E3.4 Describe, in qualitative terms, the production of electromagnetic radiation by an oscillating electric dipole (e.g., a radio transmitter, a micro-wave emitter, an X-ray emitter, electron energy transitions in an atom).
E1. Analyse technologies that use the wave nature of light, and assess their impact on society and the environment.
Specific Expectations:
E2.1 Use appropriate terminology related to the wave nature of light, including, but not limited to: diffraction, dispersion, wave interference, nodal line, phase, oscillate, polarization, and electromagnetic radiation.
E3.4 Describe, in qualitative terms, the production of electromagnetic radiation by an oscillating electric dipole (e.g., a radio transmitter, a micro-wave emitter, an X-ray emitter, electron energy transitions in an atom).
Success Criteria:
- What is electromagnetic radiation?
- What are the key ideas of Maxwell's equations?
- What are the three central properties of electromagnetic waves?
- Describe the electromagnetic spectrum.
- Describe the effect of UV radiation on humans.
Time Allocation: 2 hours
Learning Activities:
Read pages 526 - 530 from Nelson 10.4
|
Radio Waves & Electromagnetic Fields
Broadcast radio waves from PhET. Wiggle the transmitter electron manually or have it oscillate automatically. Display the field as a curve or vectors. The strip chart shows the electron positions at the transmitter and at the receiver. |
|
In the playlist below, video:
- Will show you a simple understanding of electromagnetic waves.
Practice questions 2 and 3 on page 530.
Task:
Optional Extension:
- Solve questions 3, 4, and 5 on page 531.
Reflect:
Explain why exposure to ultraviolet radiation is more dangerous to humans than exposure to visible light. Why is this? Summarize some of the dangers.
