Watch the part three of the video at the minute 1:57:00. And answers all of question below. Do not watch part one because it does not require.

Link of the video: https://www.youtube.com/watch?v=Gtp51eZkwoI&t=7033s

Questions:

1. What did James Clerk Maxwell do to advance the science of electricity?
2. What did Maxwell predict?
3. What did Maxwell's work inspire Heinrich Heinz to do?
4. Hertz set up a device that generates an alternating current that travels along metal rods. According to Maxwell's equations, this should produce invisible electromagnetic waves, which would spread out into the room. Hertz built a ring of wire as a receiver that he could carry to different positions around the room so that he could map out the shape of the waves in order to test Maxwell's calculations. How could the wire ring help him find evidence of the electromagnetic waves?
5. How did Oliver Lodge use iron filings to improve the ability to detect the electromagnetic waves with Hertz's receiver?
6. Lodge's demonstration inspired Guglielmo Marconi to put together his own wireless telegraph system. What skill did Marconi rely on to gain access to the resources he needed for his experiments?
7. Marconi connected with William Preece, the Engineer-in-Chief for the British post office. Marconi and Preece worked together on the rooftops of separate buildings practicing sending and receiving electromagnetic signals. What was the purpose of this activity?
8. Jagadish Chandra Bose had degrees from two prestigious universities. Why was it still difficult for him to get a job as a scientist?
9. What was the first semiconductor discovered (by Jagadish Chandra Bose)? What did it do?
10. What items in your lab kit (that we have introduced in the reading assignments so far) also do?
11. In the early 1800s, scientists and engineers found many ways to use electric current, but they still didn't know what it was. What did scientists have to do before they could understand what electric current was?
12. According to the video, why do metals conduct electricity?
13. According to the video, why don't insulators conduct electricity?
14. In 1897, through experiments with with cathode ray tubes, Physicist J. J. Thomson made an important discovery leading to a much better understanding of electricity. What did the "rays" in cathode ray tubes turn out to be?
15. What charge do electrons carry?
16. How does charge move in a cathode ray tube?
17. How does this compare to earlier semiconductors?
18. What were the newly invented vacuum tubes called?
19. Why were silicon crystals used to replace valves in some applications (like radar)?
20. What use did vacuum tubes still serve before the invention of the transistor (that allowed signals to be transmitted all over the globe)?