Watch the part two of the video at the minute 58:00, which is the part two. Do not watch part one because it does not require. \

Link of the video:

https://www.youtube.com/watch?v=Gtp51eZkwoI&t=3510s

Question:

1. In 1812, a young Michael Faraday was inspired by a demonstration given by Sir Humphry Davy at the Royal Institute. What did Davy demonstrate? (Hint: This question connects the second video to the first video that you watched previously.)
2. Han Christian Oersted made an extraordinary discovery in 1820 when he passed electric current through a copper rod. What happened, and what did this show?
3. Building on Oersted's discovery, Faraday demonstrated the relationship between what 3 important concepts? (This is a great example of iterative process at work.)
4. What components did Faraday use in the device that demonstrated this relationship? What kind of device did Faraday invent when he built the circuit that included a mercury bath?
5. What property of mercury made Faraday's motor possible?
6. Faraday moved a magnet in and out through a wire coil. What effect did he discover in this experiment?
7. In another great example of iterative process, Faraday tried spinning a copper disk in a magnetic field. What was the exciting result of this arrangement?
8. How was Faraday's copper disk device different from a battery?
9. Faraday's copper disk device illustrated an important discovery: the principle of induction. Induction is still commonly used for generating electric current today. Based on the video's description of Faraday's experiments, how does induction work? [Note: There is a caption error in the video at this point: The narrator says that Faraday discovered induction, but the caption says he discovered conduction. The narrator was correct; Faraday discovered induction. People already knew about conduction by that point.]
10. According to Professor Al-Khalili, what invention first brought electricity out of the laboratory and into the hands of ordinary people?
11. The telegraph depended on the use of electromagnets (magnets controlled by electric current). What is the main variable that determines the strength of an electromagnet?
12. Why did Henry and Sturgeon start putting iron in the center of an electromagnet's wire coil?
13. When the first trans-oceanic telegraph cable was successfully in place, Queen Elizabeth sent a congratulatory message to President Buchanan, but the message took 16 hours to get through, because the signal was unclear. Eventually, the cable stopped working entirely. What caused the cable to stop working?
14. The first electric lights to replace gas lamps were electric arc lights, demonstrated by Sir Humphrey Davy. These used 2 carbon rods, and produced white light when electricity arced across the rods. What was the problem with these lights that prevented them from being used in people's homes?
15. Since the arc lamps could not be used in homes, various engineers and inventors worked to develop a more marketable incandescent light bulb. Sir Joseph Swan partnered with Thomas Edison's company to produce and market the first incandescent bulbs for home use. How does the incandescent light bulb work?
16. Edison tried building an incandescent light bulb with a filament made of platinum. Why didn't platinum work for the light bulb filament?
17. If two resistors are made from the same material, which will have greater resistance, a THINNER filament, or a THICKER filament?
18. If two resistors are made from the same material, but one is thinner than the other, which of the two will conduct more current (if they have the same voltage across them)?
19. How did Edison propose to make electricity safer and less intrusive?
20. What did Edison say made his direct current system safer than either gas or electric arc lamps for lighting the home?
21. Nikola Tesla proposed a new method of transmitting electricity. What made it different from Edison's method?
22. Why did Tesla think a new method of power transmission was needed?
23. How did Tesla's method of power transmission solve the problems that came with Edison's method?
24. Today, we regularly use both direct current and alternating current. Give specific examples showing the use of each type from everyday life. (Note that internet sources may refer to complex systems. If you claim that an appliance that plugs into the wall uses direct current, or that a battery powered device uses alternating current, you must provide an explanation in order to receive credit.)
25. In the end, Tesla and Westinghouse won the "current war", partially thanks to Tesla's ingenious motor design that used alternating current. Prior to his design, there was no known way to use alternating current to make a motor move continuously. How did he solve the problem?
26. Nikola Tesla found a way to make even very high voltages harmless, by alternating the current at very high frequencies. However, household current is supplied at a relatively low frequency (60 hertz). Although it is safer in the US at 120V than in Europe at 240V, it is still POTENTIALLY LETHAL. Only a very small current is necessary to kill you, if it passes through your heart. The amount of ___ that passes through you depends on your body's resistance and the voltage applied across you.
27. Car batteries, although they can supply very high amounts of current, are relatively safe at only 12V DC, while common household appliances that use small current require safety circuits to prevent harm from 120V AC. The power adapter in your Lab Kit includes a wall transformer that uses INDUCTION to convert 120V AC to 9V DC. The ___ in your power adapter means your circuits will never risk connecting other components to household current. Even if it completely fails, it will provide 0V and you will remain safe.
28. What did you find most interesting to learn from this video?