1. Day 120, Monday, 14 March, 2016 Radio Day with Schematics Questions Δ V Antennas Variable Capacitors Variable Inductors Radio Logic Gates

3. Question 1 1. Why doesn’t an electric eel electrocute itself when it discharges?

4. Answer 1 The eel is typically 10 times longer than its prey. That means it has 10 3 times the volume (mass). So it is getting about 1/1000 th amps/kg as the prey.

6. Question 2 2. Frankenstein used lightning to animate his creation (millions of volts). What voltage would be needed to stimulate a cell?

7. Answer 2 28mV. (Peak action potential of a cell membrane)

8. It is not the voltage that is dangerous

9. It’s ΔV that’s important Squirrels cause many blackouts by short circuiting power circuits

10. Curious but uneducated minds do not mix well with electricity Squirrel guard

11. Curious and educated minds know no boundaries

12. Antennas An antenna (or aerial) is a transducer designed to transmit or receive electromagnetic waves. In other words, antennas convert electromagnetic waves into electrical currents and vice versa.

13. Resonant Frequency The "resonant frequency” and "electrical resonance" is related to the electrical length of an antenna. The electrical length is usually the physical length of the wire divided by its velocity factor (the ratio of the speed of wave propagation in the wire to C, the speed of light in a vacuum). Typically an antenna is tuned for a specific frequency, and is effective for a range of frequencies that are usually centered on that resonant frequency.

14. Antenna Length ½ wavelength is best

15. Capacitor 2 plates and a gap A variable capacitor The capacitance limits the frequency of transmitted messages

16. Variable Capacitors as Frequency Filters

17. Schematics of a Radio Antenna Variable capacitor (tuner) RF amplifier (transistor) Detector (Diode) Audio amplifier (transistor) Power Amplifier (transistor) Speaker

18. AM radio

19. Simple (low power) AM Radio Antenna Variable Inductor (frequency control – high end) Variable Capacitor (frequency control – low end) Diode (detector) Ear Bud

20. Variable Capacitor

21. Variable inductor

22. Speaker

23. Simple (passive) AM radio

24. Improvements too the simple AM radio

26. Circuit Schematics Activity Match the name with the property with the schematic element (picture).

27. AND Gate

28. OR Gate

29. Truth Tables for AND Gates and OR Gates

30. Credits Capacitor www.yourdictionary.com profesanxenxo.iespana.es/electrical/capacitor. jpg www.play-hooky.com Start capacitor www.herbach.com

31. Credits II Squirrel Guard Electrocuted Squirrel photo www.newscientist.com/.../labels/Animals.h tml www.newscientist.com/.../labels/Animals.h tml Jedi Squirrels joanharvest.files.wordpress.com/2008/02/s quir... http://www.usatoday.com/news/nation/2007-03-11-suicide- squirrels_N.htm

32. Credits III Variable Capacitor diagram http://www.iop.org/activity/education/Proj ects/Teaching%20Advanced%20Physics/El ectricity/Capacitors/index.html Variable Capacitor Photo http://www.stormwise.com/amvc384b.JPG

33. Credits IV Antennas Wikipedia Resonant Frequency Wikipedia Simple Radio schematics www.crystalradio.net Radio with Loop Antenna schematic http://makearadio.com/crystal/crystal- schematics.php

34. Credits V AND Gate Diagram http://hyperphysics.phy-astr.gsu.edu Or Gate diagram http://hyperphysics.phy-astr.gsu.edu