Summary

• Maxwell's equations

Example #1


• Electromagnetic radiation
  • review Maxwell's equations
  • electromagnetic waves applet
    another applet
  • the speed of light
    Example #2
    
    
  • electromagnetic spectrum
    Example #3
    
    
  • energy delivered by EM waves
    Example #4
    
    
  
  
  

klm
A light bulb can be lit from the induced currents coming from a changing magnetic field. Where does the energy come from?
A. Energy stored in the wire atoms.
B. Energy stored in the magnet
C. Energy in the magnet's motion.
D. Energy in electric waves.
Answer







klm
Steve Fossett flew the Global Voyager 23,000 miles in 67 hours to circumnavigate the world. In how much time would an EM wave complete the same trip?
A. 0.123 s            B. 8.10 s
C. 76.7 µs            D. 3.62 h
Answer







klm
What is the wavelength of radio waves broadcast by AM 620 WTMJ?
A. 2.07 mm               B. 484 m
C. 1.86�10¹⁴ m          D. 3.00�10⁸ m
Answer







sj6 34.16
What is B_max for an EM wave emitted by a 10 kW radio station 5 km away?
A. 33.3 µT                 B. 338 nT
C. 0.516 nT               D. 19.5 mT
Answer







 



D. Energy in electric waves.
The changing magnetic field induces a changing electric field and the two fields carry energy in the form of an electromagnetic wave.












 



A. 0.123 s













 



B. 484 m













 



C. 0.516 nT