user-avatar
baochau123
2 năm trước
giải giúp em với ạ :(( 1.Công thoát của electron ra khỏi vônfram là A = 7,2.10-19 J chiếu vào vônfram bức xạ có bước sóng 0,18 micro m thì động năng cực đại của electron khi bức ra khỏi vônfram là: 2. Chiếu bức xạ tử ngoại có lamđa = 0,25 micro m vào một tấm kim loại có công thoát 3,45 eV. Vận tốc ban đầu cực đại của êlectron quang điện là:
Thích Trả lời Chia sẻ

Các câu hỏi liên quan

X. Read the passage carefully, then do the tasks. For hundreds of years, one remote hill in the middle of England has hosted one of the weirdest and most hazardous festivals in the world. It’s the Cooper’s Hill Cheese Rolling Festival. The event is held every year at the end of May. Some people believe that the festival originated from a tradition of rolling burning bundles ofsticks down the hill to celebrate the end of winter. Today, the festival has grown into an international event, with over 15,000 participants and spectators from all over the world joining each year. The rules are simple. A large wheel of cheese is rolled down the hill, and participants chase after it. The first runner to make it to the bottom of the hill is the winner. The winner of the race is allowed to keep the cheese as a prize. Cooper’s Hill is only 200 meters long, but it is very steep. As a result, racers do not run down the hill; instead, they usually fall down the hill head over heels. This has led to a lot of accidents. For this reason, the event was officially canceled in 2010. Outraged fans have continued the event unofficially since then. A. Match the words or phrases with their definitions. 1. hazardous 2. originate 3. bundle 4. remote 5. fall head over heels a. a group of things that are tied or wrapped together. b. to roll or fall down out of control c. to start in a particular situation d. dangerous, especially to people’s health or safety e. far away from places where people live B. Choose the correct answers. 1. What is the passage mainly about? a. Different food festivals around the world b. An unusual and dangerous festival in England c. Tips for winning the race in the Cheese Rolling Festival d. The history of the Cheese Rolling Festival 2. What is the origin of the Cheese Rolling Festival? a. It is held every year in May. b. It takes place at Cooper’s Hill in Gloucestershire. c. It is held to represent the birth of the New Year after winter. d. It comes from the tradition of rolling burning bundles of sticks down the hill. 3. The word ‘outraged’ in the last sentence is closest in meaning to _______. a. upset b. pleasant c. keen d. big 4. According to the passage, which of the following is true? a. All the runners in the race are from England. b. The race is dangerous because the hill is very long. c. Most participants cannot stay on their feet while they run down the hill. d. The winner is the first person to catch the cheese. 5. The festival was officially canceled in 2010 due to _________________________________. a. a large number of participants b. the bad weather in Gloucestershire c. the steep slopes of Cooper’s Hill d. the dangerous aspect of the event

IV. Read the text and choose the best answers. SAFETY TIPS FOR BUS PASSENGERS Always maintain a queue while waiting (1)______ a bus. Never stand on queue on the middle of the road. At the time of boarding a bus do not try to run or chase the bus. Once you are inside the bus, (2)______ a seat and hold firmly on the handrail if you are standing. Never try to (3)______ an overcrowded bus. Avoid (4)______ inside of a bus because your high-pitch noise may distract the attention of the driver and it could lead to a major (5)______ accident. 1.A.for B.to C.on D.in 2.A.hold B.sit C.take D.find 3.A.choose B.go C.wait D.board 4.A.shout B.shouting C.to shout D.shouts 5.A.road B.way C.path D.street D. WRITING I. Rewrite the sentences with the same meaning. (Viết lại câu sao cho nghĩa của câu không đổi) 1. The distance from Ha Noi to Thanh Hoa city is about 100 km. It is about……………………............................................................................. 2. What is the distance between Ho Chi Minh city to Hue? How………..…………………………………………….…..……..……… .. 3.My father lived in small village when he was a child. My father used to ……………………………..…………….…….. 4. Although Quang Hai is so young, he plays football beautifully. Despite .................................................................................................... 5. I often walked to school when I was a student. I used………………..……………………………………………………… 6. In spite of being so young, Tien Dung goalkeeper performs excellently. Although………………………………………………………….……… 7, 8. Although they are short, they still love playing sports. In spite of…………………………………………………………… …………………………………………………………………………(BUT) 9. Vietnam is a small country but it has many festivals during the year Although ……………………………………………………………………… 10. There wasn’t a big shopping center here when we was young. There did……………………………………………………………………… 11. She watched a horror film last night. A horror film …………………………………………………………………… 12. The festival took place in a remote area. However, a lot of people attended it. Although ………………………………………………………………………… 13.This wet weather is so depressing. …………………………………………………………………………(MAKES) 14.I was very disappointed not to get the job. ………………………………………………………………(DISAPPOINTING) 15.Her behaviour annoyed her teachers. ………………………………………………………………………(FOUND) 16.I thought the ending of the film is quite shocking. ………………………………………………………………………...........(AT) 17.I feel very relaxed when I see a romantic comedy. ………………………………………………………………………(SEEING)

2018 © Loga - Không Ngừng Sáng Tạo - Bùng Cháy Đam Mê
Loga Team