Unit 16 Scientists at work

Ancient Greece static electricitystatic electricity 1745 Leyden jarLeyden jar 1880 Electrical bulb (Edison)Electrical bulb 1923 Television 1943 Computer 1989 World-wide web 1993 Human embryos cloned 1997 Dolly, the sheep, the first cloned animal A list of some important Discoveries & Inventions

Static electricity

Leyden jar ( 莱顿瓶 )

Edison

Life without electricity

Benjamin Franklin ( ) Benjamin Franklin Statesman, scientist, inventor, publisher of the Pennsylvania Gazette, member of the Continental Congress and the Constitutional Convention, signer of the Declaration of Independence, first U.S. Postmaster General, American commissioner to Paris.

Pre-reading Find the words that fit the descriptions c______ lead or guide (sb. /sth.) c______ amount of electricity put into a battery or contained in a substance p______ show that sth is true or certain by means of argument or evidence( 证据 ) t______ pull (sth) forcibly apart or away or to pieces f______ firmly attach sth to sth or two things together e______ make sth clear or easy to understand a______ become visible onduct harge rove ear asten xplain ppear

While-reading Look at the textbook and listen to the tape carefully, then try to complete the following chart. Task 1

Name Time Attendee Purpose Things needed A record of the experiment Kite Experiment Franklin and his son Lightning and electricity are the same. a kite, a key, some really bad weather and a condenser In June 1752

Task 2 Read the text quickly and try to get the main idea of each paragraph.

to make a special kite for the experiment? should be done to get ready for the experiment? to do the experiment with a kite, a key and a condenser? did Franklin succeed in doing the experiment? did Franklin do the experiment Why Franklin ’ s famous kite experiment Para 1 Para 2 Para 3 Para 4 Para 5 Para 6 Introduction How What How Process of the experiment The tips of doing the experiment

Read the text carefully, then do some exercises. Task 3

Exercise 1 Multiple choice 1.Franklin made the kite of silk because ______. A. wet silk does not conduct electricity B. silk kite flies high C. silk kite will last longer in weather with rain and strong winds D. silk kite is cheaper C. silk kite will last longer in weather with rain and strong winds

2. Which is not stated but can be inferred from the text? A. Franklin did the experiment with the kite. B. Franklin ’ s experiment with electricity was dangerous. C. Franklin failed the experiment again. D. The experiment was conducted in bad weather. B. Franklin ’ s experiment with electricity was dangerous.

3. Which of the following is in the correct order? ① The experiment proves that lightning and electricity are the same. ② The kite flew high in the rainy sky. ③ He made a silk kite. ④ Very sharp piece of metal was fixed. ⑤ A key was fastened to the end of the string. ⑥ A ribbon was tied to the string. A. ④ ⑤ ⑥ ③ ② ① B. ③ ④ ⑤ ⑥ ② ① C. ④ ③ ⑤ ⑥ ① ② D. ③ ④ ⑤ ⑥ ① ②

Franklin's Kite Experiment

Exercise 2 Demonstration Draw a sketch( 草图 ) of the kite which was used in the experiment according to the instruction.

Instruction ① A small cross of two pieces of light wood. ② Tie the corners of a handkerchief to the points of the cross. ③ Add a tail to the frame. ④ Tie a long string to the cross. ⑤ Fix a sharp piece of metal to the top of the longer stick of the cross. ⑥ Fasten a key to the end of the long string. ⑦ Tie a silk ribbon to the string.

sharp piece of metal One foot or more Long string “ cross ” tail Silk ribbon

Post-reading Finish the exercise on page 25 in group of four.

Homework 1.Try to retell the text after class. 2.Search and Collect more information about your favourite scientist at work on the internet.

How did Benjamin Franklin's Kite Experiment Work? Benjamin Franklin's kite experiment has grown into an American legend. Almost everyone has heard of Franklin's famous experiment, but few of us actually understand how the experiment worked. When a storm cloud passed over Franklin's kite the negative charges in the cloud leaked onto his kite, his kite string, his key, and a Leyden jar attached to the key by a thin metal wire. Franklin however, was unaffected by the negative charges because he was holding a dry silk string which insulated him from the charges on the key. When Franklin reached out his knuckle to touch the key he received a shock, because the negative charges in the key were so strongly attracted to the positive charges in his body that a spark jumped from the key to his hand. Franklin's experiment successfully showed that lightning was actually static electricity.